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66cbab2c KW |
1 | =encoding utf8 |
2 | ||
5f05dabc | 3 | =head1 NAME |
4 | ||
b0c42ed9 | 5 | perllocale - Perl locale handling (internationalization and localization) |
5f05dabc | 6 | |
7 | =head1 DESCRIPTION | |
8 | ||
66cbab2c KW |
9 | In the beginning there was ASCII, the "American Standard Code for |
10 | Information Interchange", which works quite well for Americans with | |
11 | their English alphabet and dollar-denominated currency. But it doesn't | |
12 | work so well even for other English speakers, who may use different | |
13 | currencies, such as the pound sterling (as the symbol for that currency | |
14 | is not in ASCII); and it's hopelessly inadequate for many of the | |
15 | thousands of the world's other languages. | |
16 | ||
17 | To address these deficiencies, the concept of locales was invented | |
18 | (formally the ISO C, XPG4, POSIX 1.c "locale system"). And applications | |
19 | were and are being written that use the locale mechanism. The process of | |
20 | making such an application take account of its users' preferences in | |
21 | these kinds of matters is called B<internationalization> (often | |
22 | abbreviated as B<i18n>); telling such an application about a particular | |
23 | set of preferences is known as B<localization> (B<l10n>). | |
24 | ||
0c880285 KW |
25 | Perl has been extended to support certain types of locales available in |
26 | the locale system. This is controlled per application by using one | |
27 | pragma, one function call, and several environment variables. | |
28 | ||
29 | Perl supports single-byte locales that are supersets of ASCII, such as | |
30 | the ISO 8859 ones, and one multi-byte-type locale, UTF-8 ones, described | |
31 | in the next paragraph. Perl doesn't support any other multi-byte | |
32 | locales, such as the ones for East Asian languages. | |
66cbab2c KW |
33 | |
34 | Unfortunately, there are quite a few deficiencies with the design (and | |
31f05a37 KW |
35 | often, the implementations) of locales. Unicode was invented (see |
36 | L<perlunitut> for an introduction to that) in part to address these | |
37 | design deficiencies, and nowadays, there is a series of "UTF-8 | |
38 | locales", based on Unicode. These are locales whose character set is | |
39 | Unicode, encoded in UTF-8. Starting in v5.20, Perl fully supports | |
9accf6df | 40 | UTF-8 locales, except for sorting and string comparisons like C<lt> and |
a4a439fb KW |
41 | C<ge>. Starting in v5.26, Perl can handle these reasonably as well, |
42 | depending on the platform's implementation. However, for earlier | |
0c8d0e83 KW |
43 | releases or for better control, use L<Unicode::Collate>. There are |
44 | actually two slightly different types of UTF-8 locales: one for Turkic | |
00872368 TC |
45 | languages and one for everything else. |
46 | ||
47 | Starting in Perl v5.30, Perl detects Turkic locales by their | |
48 | behaviour, and seamlessly handles both types; previously only the | |
49 | non-Turkic one was supported. The name of the locale is ignored, if | |
50 | your system has a C<tr_TR.UTF-8> locale and it doesn't behave like a | |
51 | Turkic locale, perl will treat it like a non-Turkic locale. | |
0c8d0e83 KW |
52 | |
53 | Perl continues to support the old non UTF-8 locales as well. There are | |
54 | currently no UTF-8 locales for EBCDIC platforms. | |
31f05a37 | 55 | |
66cbab2c KW |
56 | (Unicode is also creating C<CLDR>, the "Common Locale Data Repository", |
57 | L<http://cldr.unicode.org/> which includes more types of information than | |
58 | are available in the POSIX locale system. At the time of this writing, | |
59 | there was no CPAN module that provides access to this XML-encoded data. | |
e784ce68 KW |
60 | However, it is possible to compute the POSIX locale data from them, and |
61 | earlier CLDR versions had these already extracted for you as UTF-8 locales | |
62 | L<http://unicode.org/Public/cldr/2.0.1/>.) | |
66cbab2c KW |
63 | |
64 | =head1 WHAT IS A LOCALE | |
65 | ||
66 | A locale is a set of data that describes various aspects of how various | |
67 | communities in the world categorize their world. These categories are | |
68 | broken down into the following types (some of which include a brief | |
69 | note here): | |
70 | ||
71 | =over | |
72 | ||
cb88b78e | 73 | =item Category C<LC_NUMERIC>: Numeric formatting |
66cbab2c KW |
74 | |
75 | This indicates how numbers should be formatted for human readability, | |
76 | for example the character used as the decimal point. | |
77 | ||
cb88b78e | 78 | =item Category C<LC_MONETARY>: Formatting of monetary amounts |
66cbab2c | 79 | |
032639c4 | 80 | Z<> |
66cbab2c | 81 | |
cb88b78e | 82 | =item Category C<LC_TIME>: Date/Time formatting |
66cbab2c | 83 | |
032639c4 | 84 | Z<> |
66cbab2c | 85 | |
cb88b78e | 86 | =item Category C<LC_MESSAGES>: Error and other messages |
66cbab2c | 87 | |
2619d284 | 88 | This is used by Perl itself only for accessing operating system error |
03c702c5 | 89 | messages via L<$!|perlvar/$ERRNO> and L<$^E|perlvar/$EXTENDED_OS_ERROR>. |
66cbab2c | 90 | |
cb88b78e | 91 | =item Category C<LC_COLLATE>: Collation |
66cbab2c | 92 | |
76073c88 | 93 | This indicates the ordering of letters for comparison and sorting. |
66cbab2c KW |
94 | In Latin alphabets, for example, "b", generally follows "a". |
95 | ||
cb88b78e | 96 | =item Category C<LC_CTYPE>: Character Types |
66cbab2c KW |
97 | |
98 | This indicates, for example if a character is an uppercase letter. | |
99 | ||
2619d284 KW |
100 | =item Other categories |
101 | ||
102 | Some platforms have other categories, dealing with such things as | |
103 | measurement units and paper sizes. None of these are used directly by | |
104 | Perl, but outside operations that Perl interacts with may use | |
d6ded950 | 105 | these. See L</Not within the scope of "use locale"> below. |
2619d284 | 106 | |
66cbab2c KW |
107 | =back |
108 | ||
2619d284 KW |
109 | More details on the categories used by Perl are given below in L</LOCALE |
110 | CATEGORIES>. | |
66cbab2c KW |
111 | |
112 | Together, these categories go a long way towards being able to customize | |
113 | a single program to run in many different locations. But there are | |
114 | deficiencies, so keep reading. | |
5f05dabc | 115 | |
116 | =head1 PREPARING TO USE LOCALES | |
117 | ||
c5c88224 KW |
118 | Perl itself (outside the L<POSIX> module) will not use locales unless |
119 | specifically requested to (but | |
2619d284 KW |
120 | again note that Perl may interact with code that does use them). Even |
121 | if there is such a request, B<all> of the following must be true | |
b960a36e | 122 | for it to work properly: |
5f05dabc | 123 | |
124 | =over 4 | |
125 | ||
126 | =item * | |
127 | ||
128 | B<Your operating system must support the locale system>. If it does, | |
39332f68 | 129 | you should find that the C<setlocale()> function is a documented part of |
5f05dabc | 130 | its C library. |
131 | ||
132 | =item * | |
133 | ||
5a964f20 | 134 | B<Definitions for locales that you use must be installed>. You, or |
14280422 DD |
135 | your system administrator, must make sure that this is the case. The |
136 | available locales, the location in which they are kept, and the manner | |
5a964f20 TC |
137 | in which they are installed all vary from system to system. Some systems |
138 | provide only a few, hard-wired locales and do not allow more to be | |
139 | added. Others allow you to add "canned" locales provided by the system | |
140 | supplier. Still others allow you or the system administrator to define | |
14280422 | 141 | and add arbitrary locales. (You may have to ask your supplier to |
5a964f20 | 142 | provide canned locales that are not delivered with your operating |
14280422 | 143 | system.) Read your system documentation for further illumination. |
5f05dabc | 144 | |
145 | =item * | |
146 | ||
147 | B<Perl must believe that the locale system is supported>. If it does, | |
148 | C<perl -V:d_setlocale> will say that the value for C<d_setlocale> is | |
149 | C<define>. | |
150 | ||
151 | =back | |
152 | ||
153 | If you want a Perl application to process and present your data | |
154 | according to a particular locale, the application code should include | |
5a0de581 | 155 | the S<C<use locale>> pragma (see L</The "use locale" pragma>) where |
5f05dabc | 156 | appropriate, and B<at least one> of the following must be true: |
157 | ||
158 | =over 4 | |
159 | ||
c052850d | 160 | =item 1 |
5f05dabc | 161 | |
66cbab2c | 162 | B<The locale-determining environment variables (see L</"ENVIRONMENT">) |
5a964f20 | 163 | must be correctly set up> at the time the application is started, either |
ef3087ec | 164 | by yourself or by whomever set up your system account; or |
5f05dabc | 165 | |
c052850d | 166 | =item 2 |
5f05dabc | 167 | |
14280422 | 168 | B<The application must set its own locale> using the method described in |
5a0de581 | 169 | L</The setlocale function>. |
5f05dabc | 170 | |
171 | =back | |
172 | ||
173 | =head1 USING LOCALES | |
174 | ||
d6ded950 | 175 | =head2 The C<"use locale"> pragma |
5f05dabc | 176 | |
e9bc6d6b KW |
177 | Starting in Perl 5.28, this pragma may be used in |
178 | L<multi-threaded|threads> applications on systems that have thread-safe | |
179 | locale ability. Some caveats apply, see L</Multi-threaded> below. On | |
180 | systems without this capability, or in earlier Perls, do NOT use this | |
181 | pragma in scripts that have multiple L<threads|threads> active. The | |
182 | locale in these cases is not local to a single thread. Another thread | |
183 | may change the locale at any time, which could cause at a minimum that a | |
184 | given thread is operating in a locale it isn't expecting to be in. On | |
185 | some platforms, segfaults can also occur. The locale change need not be | |
186 | explicit; some operations cause perl to change the locale itself. You | |
187 | are vulnerable simply by having done a S<C<"use locale">>. | |
fc82b82e | 188 | |
c5c88224 KW |
189 | By default, Perl itself (outside the L<POSIX> module) |
190 | ignores the current locale. The S<C<use locale>> | |
66cbab2c | 191 | pragma tells Perl to use the current locale for some operations. |
d6ded950 KW |
192 | Starting in v5.16, there are optional parameters to this pragma, |
193 | described below, which restrict which operations are affected by it. | |
c052850d KW |
194 | |
195 | The current locale is set at execution time by | |
196 | L<setlocale()|/The setlocale function> described below. If that function | |
197 | hasn't yet been called in the course of the program's execution, the | |
66cbab2c | 198 | current locale is that which was determined by the L</"ENVIRONMENT"> in |
ebc3223b | 199 | effect at the start of the program. |
dfcc8045 | 200 | If there is no valid environment, the current locale is whatever the |
65ebb059 KW |
201 | system default has been set to. On POSIX systems, it is likely, but |
202 | not necessarily, the "C" locale. On Windows, the default is set via the | |
203 | computer's S<C<Control Panel-E<gt>Regional and Language Options>> (or its | |
204 | current equivalent). | |
c052850d KW |
205 | |
206 | The operations that are affected by locale are: | |
5f05dabc | 207 | |
208 | =over 4 | |
209 | ||
d6ded950 | 210 | =item B<Not within the scope of C<"use locale">> |
b960a36e | 211 | |
c0a087f2 KW |
212 | Only certain operations (all originating outside Perl) should be |
213 | affected, as follows: | |
1d2ab946 KW |
214 | |
215 | =over 4 | |
216 | ||
217 | =item * | |
2619d284 | 218 | |
663d437a | 219 | The current locale is used when going outside of Perl with |
2619d284 KW |
220 | operations like L<system()|perlfunc/system LIST> or |
221 | L<qxE<sol>E<sol>|perlop/qxE<sol>STRINGE<sol>>, if those operations are | |
222 | locale-sensitive. | |
223 | ||
1d2ab946 KW |
224 | =item * |
225 | ||
2619d284 KW |
226 | Also Perl gives access to various C library functions through the |
227 | L<POSIX> module. Some of those functions are always affected by the | |
228 | current locale. For example, C<POSIX::strftime()> uses C<LC_TIME>; | |
229 | C<POSIX::strtod()> uses C<LC_NUMERIC>; C<POSIX::strcoll()> and | |
9accf6df | 230 | C<POSIX::strxfrm()> use C<LC_COLLATE>. All such functions |
2619d284 | 231 | will behave according to the current underlying locale, even if that |
1d2ab946 | 232 | locale isn't exposed to Perl space. |
2619d284 | 233 | |
d9e2553c KW |
234 | This applies as well to L<I18N::Langinfo>. |
235 | ||
1d2ab946 KW |
236 | =item * |
237 | ||
52686f2a KW |
238 | XS modules for all categories but C<LC_NUMERIC> get the underlying |
239 | locale, and hence any C library functions they call will use that | |
8a384d3a | 240 | underlying locale. For more discussion, see L<perlxs/CAVEATS>. |
1d2ab946 KW |
241 | |
242 | =back | |
243 | ||
c5c88224 KW |
244 | Note that all C programs (including the perl interpreter, which is |
245 | written in C) always have an underlying locale. That locale is the "C" | |
246 | locale unless changed by a call to L<setlocale()|/The setlocale | |
247 | function>. When Perl starts up, it changes the underlying locale to the | |
248 | one which is indicated by the L</ENVIRONMENT>. When using the L<POSIX> | |
249 | module or writing XS code, it is important to keep in mind that the | |
250 | underlying locale may be something other than "C", even if the program | |
251 | hasn't explicitly changed it. | |
252 | ||
032639c4 | 253 | Z<> |
ebc3223b KW |
254 | |
255 | =item B<Lingering effects of C<S<use locale>>> | |
1d2ab946 KW |
256 | |
257 | Certain Perl operations that are set-up within the scope of a | |
d6ded950 | 258 | C<use locale> retain that effect even outside the scope. |
b960a36e KW |
259 | These include: |
260 | ||
261 | =over 4 | |
262 | ||
263 | =item * | |
264 | ||
265 | The output format of a L<write()|perlfunc/write> is determined by an | |
266 | earlier format declaration (L<perlfunc/format>), so whether or not the | |
267 | output is affected by locale is determined by if the C<format()> is | |
d6ded950 | 268 | within the scope of a C<use locale>, not whether the C<write()> |
b960a36e KW |
269 | is. |
270 | ||
271 | =item * | |
272 | ||
273 | Regular expression patterns can be compiled using | |
33be4c61 | 274 | L<qrE<sol>E<sol>|perlop/qrE<sol>STRINGE<sol>msixpodualn> with actual |
b960a36e KW |
275 | matching deferred to later. Again, it is whether or not the compilation |
276 | was done within the scope of C<use locale> that determines the match | |
277 | behavior, not if the matches are done within such a scope or not. | |
278 | ||
279 | =back | |
280 | ||
032639c4 | 281 | Z<> |
ebc3223b | 282 | |
d6ded950 | 283 | =item B<Under C<"use locale";>> |
66cbab2c KW |
284 | |
285 | =over 4 | |
286 | ||
287 | =item * | |
288 | ||
d6ded950 | 289 | All the above operations |
b960a36e KW |
290 | |
291 | =item * | |
292 | ||
293 | B<Format declarations> (L<perlfunc/format>) and hence any subsequent | |
294 | C<write()>s use C<LC_NUMERIC>. | |
66cbab2c KW |
295 | |
296 | =item * | |
297 | ||
b960a36e KW |
298 | B<stringification and output> use C<LC_NUMERIC>. |
299 | These include the results of | |
300 | C<print()>, | |
301 | C<printf()>, | |
302 | C<say()>, | |
303 | and | |
304 | C<sprintf()>. | |
66cbab2c | 305 | |
b960a36e KW |
306 | =item * |
307 | ||
308 | B<The comparison operators> (C<lt>, C<le>, C<cmp>, C<ge>, and C<gt>) use | |
39332f68 | 309 | C<LC_COLLATE>. C<sort()> is also affected if used without an |
5a964f20 | 310 | explicit comparison function, because it uses C<cmp> by default. |
14280422 | 311 | |
5a964f20 | 312 | B<Note:> C<eq> and C<ne> are unaffected by locale: they always |
de108802 | 313 | perform a char-by-char comparison of their scalar operands. What's |
14280422 DD |
314 | more, if C<cmp> finds that its operands are equal according to the |
315 | collation sequence specified by the current locale, it goes on to | |
de108802 RGS |
316 | perform a char-by-char comparison, and only returns I<0> (equal) if the |
317 | operands are char-for-char identical. If you really want to know whether | |
5a964f20 | 318 | two strings--which C<eq> and C<cmp> may consider different--are equal |
14280422 | 319 | as far as collation in the locale is concerned, see the discussion in |
d38c72a5 | 320 | L</Category C<LC_COLLATE>: Collation>. |
5f05dabc | 321 | |
322 | =item * | |
323 | ||
39332f68 KW |
324 | B<Regular expressions and case-modification functions> (C<uc()>, C<lc()>, |
325 | C<ucfirst()>, and C<lcfirst()>) use C<LC_CTYPE> | |
5f05dabc | 326 | |
2c6ee1a7 KW |
327 | =item * |
328 | ||
dbf3c4d7 KW |
329 | B<The variables L<$!|perlvar/$ERRNO>> (and its synonyms C<$ERRNO> and |
330 | C<$OS_ERROR>) B<and L<$^E|perlvar/$EXTENDED_OS_ERROR>> (and its synonym | |
2c6ee1a7 KW |
331 | C<$EXTENDED_OS_ERROR>) when used as strings use C<LC_MESSAGES>. |
332 | ||
5f05dabc | 333 | =back |
334 | ||
66cbab2c | 335 | =back |
5f05dabc | 336 | |
5a964f20 | 337 | The default behavior is restored with the S<C<no locale>> pragma, or |
ef3087ec | 338 | upon reaching the end of the block enclosing C<use locale>. |
3cd61afa | 339 | Note that C<use locale> calls may be |
66cbab2c KW |
340 | nested, and that what is in effect within an inner scope will revert to |
341 | the outer scope's rules at the end of the inner scope. | |
5f05dabc | 342 | |
5a964f20 | 343 | The string result of any operation that uses locale |
14280422 | 344 | information is tainted, as it is possible for a locale to be |
5a0de581 | 345 | untrustworthy. See L</"SECURITY">. |
5f05dabc | 346 | |
d6ded950 KW |
347 | Starting in Perl v5.16 in a very limited way, and more generally in |
348 | v5.22, you can restrict which category or categories are enabled by this | |
349 | particular instance of the pragma by adding parameters to it. For | |
350 | example, | |
351 | ||
352 | use locale qw(:ctype :numeric); | |
353 | ||
354 | enables locale awareness within its scope of only those operations | |
355 | (listed above) that are affected by C<LC_CTYPE> and C<LC_NUMERIC>. | |
356 | ||
357 | The possible categories are: C<:collate>, C<:ctype>, C<:messages>, | |
358 | C<:monetary>, C<:numeric>, C<:time>, and the pseudo category | |
359 | C<:characters> (described below). | |
360 | ||
361 | Thus you can say | |
362 | ||
363 | use locale ':messages'; | |
364 | ||
365 | and only L<$!|perlvar/$ERRNO> and L<$^E|perlvar/$EXTENDED_OS_ERROR> | |
366 | will be locale aware. Everything else is unaffected. | |
367 | ||
368 | Since Perl doesn't currently do anything with the C<LC_MONETARY> | |
369 | category, specifying C<:monetary> does effectively nothing. Some | |
22803c6a | 370 | systems have other categories, such as C<LC_PAPER>, but Perl |
e9bc6d6b | 371 | also doesn't do anything with them, and there is no way to specify |
d6ded950 KW |
372 | them in this pragma's arguments. |
373 | ||
374 | You can also easily say to use all categories but one, by either, for | |
375 | example, | |
376 | ||
377 | use locale ':!ctype'; | |
378 | use locale ':not_ctype'; | |
379 | ||
380 | both of which mean to enable locale awarness of all categories but | |
381 | C<LC_CTYPE>. Only one category argument may be specified in a | |
382 | S<C<use locale>> if it is of the negated form. | |
383 | ||
384 | Prior to v5.22 only one form of the pragma with arguments is available: | |
385 | ||
386 | use locale ':not_characters'; | |
387 | ||
388 | (and you have to say C<not_>; you can't use the bang C<!> form). This | |
389 | pseudo category is a shorthand for specifying both C<:collate> and | |
390 | C<:ctype>. Hence, in the negated form, it is nearly the same thing as | |
391 | saying | |
392 | ||
393 | use locale qw(:messages :monetary :numeric :time); | |
394 | ||
395 | We use the term "nearly", because C<:not_characters> also turns on | |
396 | S<C<use feature 'unicode_strings'>> within its scope. This form is | |
397 | less useful in v5.20 and later, and is described fully in | |
398 | L</Unicode and UTF-8>, but briefly, it tells Perl to not use the | |
399 | character portions of the locale definition, that is the C<LC_CTYPE> and | |
400 | C<LC_COLLATE> categories. Instead it will use the native character set | |
401 | (extended by Unicode). When using this parameter, you are responsible | |
402 | for getting the external character set translated into the | |
403 | native/Unicode one (which it already will be if it is one of the | |
404 | increasingly popular UTF-8 locales). There are convenient ways of doing | |
405 | this, as described in L</Unicode and UTF-8>. | |
406 | ||
5f05dabc | 407 | =head2 The setlocale function |
408 | ||
e9bc6d6b KW |
409 | WARNING! Prior to Perl 5.28 or on a system that does not support |
410 | thread-safe locale operations, do NOT use this function in a | |
411 | L<thread|threads>. The locale will change in all other threads at the | |
412 | same time, and should your thread get paused by the operating system, | |
413 | and another started, that thread will not have the locale it is | |
414 | expecting. On some platforms, there can be a race leading to segfaults | |
415 | if two threads call this function nearly simultaneously. | |
fc82b82e | 416 | |
14280422 | 417 | You can switch locales as often as you wish at run time with the |
39332f68 | 418 | C<POSIX::setlocale()> function: |
5f05dabc | 419 | |
5f05dabc | 420 | # Import locale-handling tool set from POSIX module. |
421 | # This example uses: setlocale -- the function call | |
422 | # LC_CTYPE -- explained below | |
2619d284 KW |
423 | # (Showing the testing for success/failure of operations is |
424 | # omitted in these examples to avoid distracting from the main | |
ebc3223b | 425 | # point) |
6ea81ccf | 426 | |
5f05dabc | 427 | use POSIX qw(locale_h); |
dfcc8045 KW |
428 | use locale; |
429 | my $old_locale; | |
5f05dabc | 430 | |
14280422 | 431 | # query and save the old locale |
5f05dabc | 432 | $old_locale = setlocale(LC_CTYPE); |
433 | ||
434 | setlocale(LC_CTYPE, "fr_CA.ISO8859-1"); | |
435 | # LC_CTYPE now in locale "French, Canada, codeset ISO 8859-1" | |
436 | ||
437 | setlocale(LC_CTYPE, ""); | |
65ebb059 KW |
438 | # LC_CTYPE now reset to the default defined by the |
439 | # LC_ALL/LC_CTYPE/LANG environment variables, or to the system | |
440 | # default. See below for documentation. | |
5f05dabc | 441 | |
442 | # restore the old locale | |
443 | setlocale(LC_CTYPE, $old_locale); | |
444 | ||
39332f68 | 445 | The first argument of C<setlocale()> gives the B<category>, the second the |
14280422 DD |
446 | B<locale>. The category tells in what aspect of data processing you |
447 | want to apply locale-specific rules. Category names are discussed in | |
66cbab2c | 448 | L</LOCALE CATEGORIES> and L</"ENVIRONMENT">. The locale is the name of a |
14280422 DD |
449 | collection of customization information corresponding to a particular |
450 | combination of language, country or territory, and codeset. Read on for | |
451 | hints on the naming of locales: not all systems name locales as in the | |
452 | example. | |
453 | ||
39332f68 | 454 | If no second argument is provided and the category is something other |
cb88b78e | 455 | than C<LC_ALL>, the function returns a string naming the current locale |
502a173a | 456 | for the category. You can use this value as the second argument in a |
f170b852 KW |
457 | subsequent call to C<setlocale()>, B<but> on some platforms the string |
458 | is opaque, not something that most people would be able to decipher as | |
459 | to what locale it means. | |
502a173a | 460 | |
cb88b78e | 461 | If no second argument is provided and the category is C<LC_ALL>, the |
502a173a | 462 | result is implementation-dependent. It may be a string of |
c052850d | 463 | concatenated locale names (separator also implementation-dependent) |
39332f68 | 464 | or a single locale name. Please consult your L<setlocale(3)> man page for |
502a173a JH |
465 | details. |
466 | ||
467 | If a second argument is given and it corresponds to a valid locale, | |
468 | the locale for the category is set to that value, and the function | |
469 | returns the now-current locale value. You can then use this in yet | |
39332f68 | 470 | another call to C<setlocale()>. (In some implementations, the return |
502a173a JH |
471 | value may sometimes differ from the value you gave as the second |
472 | argument--think of it as an alias for the value you gave.) | |
5f05dabc | 473 | |
474 | As the example shows, if the second argument is an empty string, the | |
475 | category's locale is returned to the default specified by the | |
476 | corresponding environment variables. Generally, this results in a | |
5a964f20 | 477 | return to the default that was in force when Perl started up: changes |
54310121 | 478 | to the environment made by the application after startup may or may not |
5a964f20 | 479 | be noticed, depending on your system's C library. |
5f05dabc | 480 | |
d6ded950 KW |
481 | Note that when a form of C<use locale> that doesn't include all |
482 | categories is specified, Perl ignores the excluded categories. | |
66cbab2c | 483 | |
f170b852 | 484 | If C<set_locale()> fails for some reason (for example, an attempt to set |
dfcc8045 KW |
485 | to a locale unknown to the system), the locale for the category is not |
486 | changed, and the function returns C<undef>. | |
487 | ||
e9bc6d6b KW |
488 | Starting in Perl 5.28, on multi-threaded perls compiled on systems that |
489 | implement POSIX 2008 thread-safe locale operations, this function | |
490 | doesn't actually call the system C<setlocale>. Instead those | |
491 | thread-safe operations are used to emulate the C<setlocale> function, | |
492 | but in a thread-safe manner. | |
2619d284 | 493 | |
44289c0b KW |
494 | You can force the thread-safe locale operations to always be used (if |
495 | available) by recompiling perl with | |
496 | ||
497 | -Accflags='-DUSE_THREAD_SAFE_LOCALE' | |
498 | ||
499 | added to your call to F<Configure>. | |
500 | ||
39332f68 | 501 | For further information about the categories, consult L<setlocale(3)>. |
3e6e419a | 502 | |
e9bc6d6b KW |
503 | =head2 Multi-threaded operation |
504 | ||
505 | Beginning in Perl 5.28, multi-threaded locale operation is supported on | |
506 | systems that implement either the POSIX 2008 or Windows-specific | |
507 | thread-safe locale operations. Many modern systems, such as various | |
508 | Unix variants and Darwin do have this. | |
509 | ||
510 | You can tell if using locales is safe on your system by looking at the | |
511 | read-only boolean variable C<${^SAFE_LOCALES}>. The value is 1 if the | |
512 | perl is not threaded, or if it is using thread-safe locale operations. | |
513 | ||
514 | Thread-safe operations are supported in Windows starting in Visual Studio | |
515 | 2005, and in systems compatible with POSIX 2008. Some platforms claim | |
516 | to support POSIX 2008, but have buggy implementations, so that the hints | |
517 | files for compiling to run on them turn off attempting to use | |
518 | thread-safety. C<${^SAFE_LOCALES}> will be 0 on them. | |
519 | ||
520 | Be aware that writing a multi-threaded application will not be portable | |
521 | to a platform which lacks the native thread-safe locale support. On | |
522 | systems that do have it, you automatically get this behavior for | |
523 | threaded perls, without having to do anything. If for some reason, you | |
524 | don't want to use this capability (perhaps the POSIX 2008 support is | |
525 | buggy on your system), you can manually compile Perl to use the old | |
526 | non-thread-safe implementation by passing the argument | |
527 | C<-Accflags='-DNO_THREAD_SAFE_LOCALE'> to F<Configure>. | |
528 | Except on Windows, this will continue to use certain of the POSIX 2008 | |
529 | functions in some situations. If these are buggy, you can pass the | |
530 | following to F<Configure> instead or additionally: | |
531 | C<-Accflags='-DNO_POSIX_2008_LOCALE'>. This will also keep the code | |
532 | from using thread-safe locales. | |
533 | C<${^SAFE_LOCALES}> will be 0 on systems that turn off the thread-safe | |
534 | operations. | |
535 | ||
e1895adc KW |
536 | Normally on unthreaded builds, the traditional C<setlocale()> is used |
537 | and not the thread-safe locale functions. You can force the use of these | |
538 | on systems that have them by adding the | |
539 | C<-Accflags='-DUSE_THREAD_SAFE_LOCALE'> to F<Configure>. | |
540 | ||
e9bc6d6b KW |
541 | The initial program is started up using the locale specified from the |
542 | environment, as currently, described in L</ENVIRONMENT>. All newly | |
543 | created threads start with C<LC_ALL> set to C<"C">>. Each thread may | |
544 | use C<POSIX::setlocale()> to query or switch its locale at any time, | |
545 | without affecting any other thread. All locale-dependent operations | |
546 | automatically use their thread's locale. | |
547 | ||
548 | This should be completely transparent to any applications written | |
549 | entirely in Perl (minus a few rarely encountered caveats given in the | |
550 | L</Multi-threaded> section). Information for XS module writers is given | |
551 | in L<perlxs/Locale-aware XS code>. | |
552 | ||
3e6e419a JH |
553 | =head2 Finding locales |
554 | ||
39332f68 | 555 | For locales available in your system, consult also L<setlocale(3)> to |
5a964f20 TC |
556 | see whether it leads to the list of available locales (search for the |
557 | I<SEE ALSO> section). If that fails, try the following command lines: | |
5f05dabc | 558 | |
559 | locale -a | |
560 | ||
561 | nlsinfo | |
562 | ||
563 | ls /usr/lib/nls/loc | |
564 | ||
565 | ls /usr/lib/locale | |
566 | ||
567 | ls /usr/lib/nls | |
568 | ||
b478f28d JH |
569 | ls /usr/share/locale |
570 | ||
5f05dabc | 571 | and see whether they list something resembling these |
572 | ||
2bdf8add | 573 | en_US.ISO8859-1 de_DE.ISO8859-1 ru_RU.ISO8859-5 |
502a173a | 574 | en_US.iso88591 de_DE.iso88591 ru_RU.iso88595 |
2bdf8add | 575 | en_US de_DE ru_RU |
14280422 | 576 | en de ru |
2bdf8add JH |
577 | english german russian |
578 | english.iso88591 german.iso88591 russian.iso88595 | |
502a173a | 579 | english.roman8 russian.koi8r |
5f05dabc | 580 | |
39332f68 | 581 | Sadly, even though the calling interface for C<setlocale()> has been |
528d65ad | 582 | standardized, names of locales and the directories where the |
5a964f20 | 583 | configuration resides have not been. The basic form of the name is |
528d65ad JH |
584 | I<language_territory>B<.>I<codeset>, but the latter parts after |
585 | I<language> are not always present. The I<language> and I<country> | |
586 | are usually from the standards B<ISO 3166> and B<ISO 639>, the | |
587 | two-letter abbreviations for the countries and the languages of the | |
588 | world, respectively. The I<codeset> part often mentions some B<ISO | |
589 | 8859> character set, the Latin codesets. For example, C<ISO 8859-1> | |
590 | is the so-called "Western European codeset" that can be used to encode | |
591 | most Western European languages adequately. Again, there are several | |
592 | ways to write even the name of that one standard. Lamentably. | |
5f05dabc | 593 | |
14280422 DD |
594 | Two special locales are worth particular mention: "C" and "POSIX". |
595 | Currently these are effectively the same locale: the difference is | |
5a964f20 TC |
596 | mainly that the first one is defined by the C standard, the second by |
597 | the POSIX standard. They define the B<default locale> in which | |
14280422 | 598 | every program starts in the absence of locale information in its |
5a964f20 | 599 | environment. (The I<default> default locale, if you will.) Its language |
39332f68 KW |
600 | is (American) English and its character codeset ASCII or, rarely, a |
601 | superset thereof (such as the "DEC Multinational Character Set | |
602 | (DEC-MCS)"). B<Warning>. The C locale delivered by some vendors | |
603 | may not actually exactly match what the C standard calls for. So | |
604 | beware. | |
5f05dabc | 605 | |
14280422 DD |
606 | B<NOTE>: Not all systems have the "POSIX" locale (not all systems are |
607 | POSIX-conformant), so use "C" when you need explicitly to specify this | |
608 | default locale. | |
5f05dabc | 609 | |
3e6e419a JH |
610 | =head2 LOCALE PROBLEMS |
611 | ||
5a964f20 | 612 | You may encounter the following warning message at Perl startup: |
3e6e419a JH |
613 | |
614 | perl: warning: Setting locale failed. | |
615 | perl: warning: Please check that your locale settings: | |
616 | LC_ALL = "En_US", | |
617 | LANG = (unset) | |
618 | are supported and installed on your system. | |
619 | perl: warning: Falling back to the standard locale ("C"). | |
620 | ||
cb88b78e | 621 | This means that your locale settings had C<LC_ALL> set to "En_US" and |
5a964f20 TC |
622 | LANG exists but has no value. Perl tried to believe you but could not. |
623 | Instead, Perl gave up and fell back to the "C" locale, the default locale | |
65ebb059 KW |
624 | that is supposed to work no matter what. (On Windows, it first tries |
625 | falling back to the system default locale.) This usually means your | |
626 | locale settings were wrong, they mention locales your system has never | |
627 | heard of, or the locale installation in your system has problems (for | |
628 | example, some system files are broken or missing). There are quick and | |
629 | temporary fixes to these problems, as well as more thorough and lasting | |
630 | fixes. | |
3e6e419a | 631 | |
83fb1bf0 KW |
632 | =head2 Testing for broken locales |
633 | ||
634 | If you are building Perl from source, the Perl test suite file | |
635 | F<lib/locale.t> can be used to test the locales on your system. | |
636 | Setting the environment variable C<PERL_DEBUG_FULL_TEST> to 1 | |
637 | will cause it to output detailed results. For example, on Linux, you | |
638 | could say | |
639 | ||
1d2ab946 | 640 | PERL_DEBUG_FULL_TEST=1 ./perl -T -Ilib lib/locale.t > locale.log 2>&1 |
83fb1bf0 KW |
641 | |
642 | Besides many other tests, it will test every locale it finds on your | |
643 | system to see if they conform to the POSIX standard. If any have | |
644 | errors, it will include a summary near the end of the output of which | |
645 | locales passed all its tests, and which failed, and why. | |
646 | ||
3e6e419a JH |
647 | =head2 Temporarily fixing locale problems |
648 | ||
5a964f20 | 649 | The two quickest fixes are either to render Perl silent about any |
3e6e419a JH |
650 | locale inconsistencies or to run Perl under the default locale "C". |
651 | ||
652 | Perl's moaning about locale problems can be silenced by setting the | |
22ff3130 | 653 | environment variable C<PERL_BADLANG> to "0" or "". |
900bd440 JH |
654 | This method really just sweeps the problem under the carpet: you tell |
655 | Perl to shut up even when Perl sees that something is wrong. Do not | |
656 | be surprised if later something locale-dependent misbehaves. | |
3e6e419a JH |
657 | |
658 | Perl can be run under the "C" locale by setting the environment | |
cb88b78e KW |
659 | variable C<LC_ALL> to "C". This method is perhaps a bit more civilized |
660 | than the C<PERL_BADLANG> approach, but setting C<LC_ALL> (or | |
5a964f20 TC |
661 | other locale variables) may affect other programs as well, not just |
662 | Perl. In particular, external programs run from within Perl will see | |
3e6e419a | 663 | these changes. If you make the new settings permanent (read on), all |
5a0de581 LM |
664 | programs you run see the changes. See L</"ENVIRONMENT"> for |
665 | the full list of relevant environment variables and L</"USING LOCALES"> | |
e05ffc7d | 666 | for their effects in Perl. Effects in other programs are |
cb88b78e | 667 | easily deducible. For example, the variable C<LC_COLLATE> may well affect |
b432a672 | 668 | your B<sort> program (or whatever the program that arranges "records" |
3e6e419a JH |
669 | alphabetically in your system is called). |
670 | ||
5a964f20 TC |
671 | You can test out changing these variables temporarily, and if the |
672 | new settings seem to help, put those settings into your shell startup | |
663d437a | 673 | files. Consult your local documentation for the exact details. For |
5a964f20 | 674 | Bourne-like shells (B<sh>, B<ksh>, B<bash>, B<zsh>): |
3e6e419a JH |
675 | |
676 | LC_ALL=en_US.ISO8859-1 | |
677 | export LC_ALL | |
678 | ||
5a964f20 TC |
679 | This assumes that we saw the locale "en_US.ISO8859-1" using the commands |
680 | discussed above. We decided to try that instead of the above faulty | |
681 | locale "En_US"--and in Cshish shells (B<csh>, B<tcsh>) | |
3e6e419a JH |
682 | |
683 | setenv LC_ALL en_US.ISO8859-1 | |
c47ff5f1 | 684 | |
663d437a | 685 | or if you have the "env" application you can do (in any shell) |
c406981e JH |
686 | |
687 | env LC_ALL=en_US.ISO8859-1 perl ... | |
688 | ||
5a964f20 | 689 | If you do not know what shell you have, consult your local |
3e6e419a JH |
690 | helpdesk or the equivalent. |
691 | ||
692 | =head2 Permanently fixing locale problems | |
693 | ||
5a964f20 TC |
694 | The slower but superior fixes are when you may be able to yourself |
695 | fix the misconfiguration of your own environment variables. The | |
3e6e419a JH |
696 | mis(sing)configuration of the whole system's locales usually requires |
697 | the help of your friendly system administrator. | |
698 | ||
5a0de581 | 699 | First, see earlier in this document about L</Finding locales>. That tells |
5a964f20 TC |
700 | how to find which locales are really supported--and more importantly, |
701 | installed--on your system. In our example error message, environment | |
702 | variables affecting the locale are listed in the order of decreasing | |
703 | importance (and unset variables do not matter). Therefore, having | |
704 | LC_ALL set to "En_US" must have been the bad choice, as shown by the | |
705 | error message. First try fixing locale settings listed first. | |
3e6e419a | 706 | |
5a964f20 TC |
707 | Second, if using the listed commands you see something B<exactly> |
708 | (prefix matches do not count and case usually counts) like "En_US" | |
709 | without the quotes, then you should be okay because you are using a | |
710 | locale name that should be installed and available in your system. | |
5a0de581 | 711 | In this case, see L</Permanently fixing your system's locale configuration>. |
3e6e419a | 712 | |
4a4eefd0 | 713 | =head2 Permanently fixing your system's locale configuration |
3e6e419a | 714 | |
5a964f20 | 715 | This is when you see something like: |
3e6e419a JH |
716 | |
717 | perl: warning: Please check that your locale settings: | |
718 | LC_ALL = "En_US", | |
719 | LANG = (unset) | |
720 | are supported and installed on your system. | |
721 | ||
722 | but then cannot see that "En_US" listed by the above-mentioned | |
5a964f20 TC |
723 | commands. You may see things like "en_US.ISO8859-1", but that isn't |
724 | the same. In this case, try running under a locale | |
725 | that you can list and which somehow matches what you tried. The | |
3e6e419a | 726 | rules for matching locale names are a bit vague because |
e05ffc7d | 727 | standardization is weak in this area. See again the |
5a0de581 | 728 | L</Finding locales> about general rules. |
3e6e419a | 729 | |
b687b08b | 730 | =head2 Fixing system locale configuration |
3e6e419a | 731 | |
5a964f20 TC |
732 | Contact a system administrator (preferably your own) and report the exact |
733 | error message you get, and ask them to read this same documentation you | |
734 | are now reading. They should be able to check whether there is something | |
5a0de581 | 735 | wrong with the locale configuration of the system. The L</Finding locales> |
5a964f20 TC |
736 | section is unfortunately a bit vague about the exact commands and places |
737 | because these things are not that standardized. | |
3e6e419a | 738 | |
5f05dabc | 739 | =head2 The localeconv function |
740 | ||
39332f68 | 741 | The C<POSIX::localeconv()> function allows you to get particulars of the |
14280422 | 742 | locale-dependent numeric formatting information specified by the current |
a835cd47 KW |
743 | underlying C<LC_NUMERIC> and C<LC_MONETARY> locales (regardless of |
744 | whether called from within the scope of C<S<use locale>> or not). (If | |
745 | you just want the name of | |
39332f68 | 746 | the current locale for a particular category, use C<POSIX::setlocale()> |
5a0de581 | 747 | with a single parameter--see L</The setlocale function>.) |
5f05dabc | 748 | |
749 | use POSIX qw(locale_h); | |
5f05dabc | 750 | |
751 | # Get a reference to a hash of locale-dependent info | |
752 | $locale_values = localeconv(); | |
753 | ||
754 | # Output sorted list of the values | |
755 | for (sort keys %$locale_values) { | |
14280422 | 756 | printf "%-20s = %s\n", $_, $locale_values->{$_} |
5f05dabc | 757 | } |
758 | ||
39332f68 | 759 | C<localeconv()> takes no arguments, and returns B<a reference to> a hash. |
5a964f20 | 760 | The keys of this hash are variable names for formatting, such as |
502a173a | 761 | C<decimal_point> and C<thousands_sep>. The values are the |
cea6626f | 762 | corresponding, er, values. See L<POSIX/localeconv> for a longer |
502a173a JH |
763 | example listing the categories an implementation might be expected to |
764 | provide; some provide more and others fewer. You don't need an | |
39332f68 | 765 | explicit C<use locale>, because C<localeconv()> always observes the |
502a173a | 766 | current locale. |
5f05dabc | 767 | |
5a964f20 TC |
768 | Here's a simple-minded example program that rewrites its command-line |
769 | parameters as integers correctly formatted in the current locale: | |
5f05dabc | 770 | |
ef3087ec KW |
771 | use POSIX qw(locale_h); |
772 | ||
773 | # Get some of locale's numeric formatting parameters | |
774 | my ($thousands_sep, $grouping) = | |
775 | @{localeconv()}{'thousands_sep', 'grouping'}; | |
776 | ||
777 | # Apply defaults if values are missing | |
778 | $thousands_sep = ',' unless $thousands_sep; | |
779 | ||
780 | # grouping and mon_grouping are packed lists | |
781 | # of small integers (characters) telling the | |
782 | # grouping (thousand_seps and mon_thousand_seps | |
783 | # being the group dividers) of numbers and | |
784 | # monetary quantities. The integers' meanings: | |
785 | # 255 means no more grouping, 0 means repeat | |
786 | # the previous grouping, 1-254 means use that | |
787 | # as the current grouping. Grouping goes from | |
788 | # right to left (low to high digits). In the | |
789 | # below we cheat slightly by never using anything | |
790 | # else than the first grouping (whatever that is). | |
791 | if ($grouping) { | |
792 | @grouping = unpack("C*", $grouping); | |
793 | } else { | |
794 | @grouping = (3); | |
795 | } | |
796 | ||
797 | # Format command line params for current locale | |
798 | for (@ARGV) { | |
799 | $_ = int; # Chop non-integer part | |
800 | 1 while | |
801 | s/(\d)(\d{$grouping[0]}($|$thousands_sep))/$1$thousands_sep$2/; | |
802 | print "$_"; | |
803 | } | |
804 | print "\n"; | |
5f05dabc | 805 | |
03ceeedf KW |
806 | Note that if the platform doesn't have C<LC_NUMERIC> and/or |
807 | C<LC_MONETARY> available or enabled, the corresponding elements of the | |
808 | hash will be missing. | |
809 | ||
74c76037 | 810 | =head2 I18N::Langinfo |
4bbcc6e8 JH |
811 | |
812 | Another interface for querying locale-dependent information is the | |
c0a087f2 | 813 | C<I18N::Langinfo::langinfo()> function. |
4bbcc6e8 | 814 | |
39332f68 KW |
815 | The following example will import the C<langinfo()> function itself and |
816 | three constants to be used as arguments to C<langinfo()>: a constant for | |
74c76037 JH |
817 | the abbreviated first day of the week (the numbering starts from |
818 | Sunday = 1) and two more constants for the affirmative and negative | |
819 | answers for a yes/no question in the current locale. | |
4bbcc6e8 | 820 | |
74c76037 | 821 | use I18N::Langinfo qw(langinfo ABDAY_1 YESSTR NOSTR); |
4bbcc6e8 | 822 | |
ef3087ec KW |
823 | my ($abday_1, $yesstr, $nostr) |
824 | = map { langinfo } qw(ABDAY_1 YESSTR NOSTR); | |
4bbcc6e8 | 825 | |
74c76037 | 826 | print "$abday_1? [$yesstr/$nostr] "; |
4bbcc6e8 | 827 | |
74c76037 JH |
828 | In other words, in the "C" (or English) locale the above will probably |
829 | print something like: | |
830 | ||
e05ffc7d | 831 | Sun? [yes/no] |
4bbcc6e8 JH |
832 | |
833 | See L<I18N::Langinfo> for more information. | |
834 | ||
5f05dabc | 835 | =head1 LOCALE CATEGORIES |
836 | ||
5a964f20 TC |
837 | The following subsections describe basic locale categories. Beyond these, |
838 | some combination categories allow manipulation of more than one | |
5a0de581 | 839 | basic category at a time. See L</"ENVIRONMENT"> for a discussion of these. |
5f05dabc | 840 | |
ff52fcf1 | 841 | =head2 Category C<LC_COLLATE>: Collation: Text Comparisons and Sorting |
5f05dabc | 842 | |
d6ded950 KW |
843 | In the scope of a S<C<use locale>> form that includes collation, Perl |
844 | looks to the C<LC_COLLATE> | |
5a964f20 | 845 | environment variable to determine the application's notions on collation |
b4ffc3db TC |
846 | (ordering) of characters. For example, "b" follows "a" in Latin |
847 | alphabets, but where do "E<aacute>" and "E<aring>" belong? And while | |
f87fa335 | 848 | "color" follows "chocolate" in English, what about in traditional Spanish? |
5f05dabc | 849 | |
60f0fa02 | 850 | The following collations all make sense and you may meet any of them |
dbf3c4d7 | 851 | if you C<"use locale">. |
60f0fa02 JH |
852 | |
853 | A B C D E a b c d e | |
35316ca3 | 854 | A a B b C c D d E e |
60f0fa02 JH |
855 | a A b B c C d D e E |
856 | a b c d e A B C D E | |
857 | ||
f1cbbd6e | 858 | Here is a code snippet to tell what "word" |
5a964f20 | 859 | characters are in the current locale, in that locale's order: |
5f05dabc | 860 | |
861 | use locale; | |
35316ca3 | 862 | print +(sort grep /\w/, map { chr } 0..255), "\n"; |
5f05dabc | 863 | |
14280422 DD |
864 | Compare this with the characters that you see and their order if you |
865 | state explicitly that the locale should be ignored: | |
5f05dabc | 866 | |
867 | no locale; | |
35316ca3 | 868 | print +(sort grep /\w/, map { chr } 0..255), "\n"; |
5f05dabc | 869 | |
870 | This machine-native collation (which is what you get unless S<C<use | |
871 | locale>> has appeared earlier in the same block) must be used for | |
872 | sorting raw binary data, whereas the locale-dependent collation of the | |
b0c42ed9 | 873 | first example is useful for natural text. |
5f05dabc | 874 | |
5a0de581 | 875 | As noted in L</USING LOCALES>, C<cmp> compares according to the current |
14280422 | 876 | collation locale when C<use locale> is in effect, but falls back to a |
de108802 | 877 | char-by-char comparison for strings that the locale says are equal. You |
39332f68 | 878 | can use C<POSIX::strcoll()> if you don't want this fall-back: |
14280422 DD |
879 | |
880 | use POSIX qw(strcoll); | |
881 | $equal_in_locale = | |
882 | !strcoll("space and case ignored", "SpaceAndCaseIgnored"); | |
883 | ||
39332f68 | 884 | C<$equal_in_locale> will be true if the collation locale specifies a |
5a964f20 | 885 | dictionary-like ordering that ignores space characters completely and |
9e3a2af8 | 886 | which folds case. |
14280422 | 887 | |
a4a439fb KW |
888 | Perl uses the platform's C library collation functions C<strcoll()> and |
889 | C<strxfrm()>. That means you get whatever they give. On some | |
890 | platforms, these functions work well on UTF-8 locales, giving | |
891 | a reasonable default collation for the code points that are important in | |
892 | that locale. (And if they aren't working well, the problem may only be | |
893 | that the locale definition is deficient, so can be fixed by using a | |
894 | better definition file. Unicode's definitions (see L</Freely available | |
895 | locale definitions>) provide reasonable UTF-8 locale collation | |
896 | definitions.) Starting in Perl v5.26, Perl's use of these functions has | |
897 | been made more seamless. This may be sufficient for your needs. For | |
898 | more control, and to make sure strings containing any code point (not | |
899 | just the ones important in the locale) collate properly, the | |
900 | L<Unicode::Collate> module is suggested. | |
901 | ||
902 | In non-UTF-8 locales (hence single byte), code points above 0xFF are | |
903 | technically invalid. But if present, again starting in v5.26, they will | |
904 | collate to the same position as the highest valid code point does. This | |
905 | generally gives good results, but the collation order may be skewed if | |
906 | the valid code point gets special treatment when it forms particular | |
907 | sequences with other characters as defined by the locale. | |
908 | When two strings collate identically, the code point order is used as a | |
909 | tie breaker. | |
910 | ||
911 | If Perl detects that there are problems with the locale collation order, | |
912 | it reverts to using non-locale collation rules for that locale. | |
31f05a37 | 913 | |
5a964f20 | 914 | If you have a single string that you want to check for "equality in |
14280422 | 915 | locale" against several others, you might think you could gain a little |
39332f68 | 916 | efficiency by using C<POSIX::strxfrm()> in conjunction with C<eq>: |
14280422 DD |
917 | |
918 | use POSIX qw(strxfrm); | |
919 | $xfrm_string = strxfrm("Mixed-case string"); | |
920 | print "locale collation ignores spaces\n" | |
921 | if $xfrm_string eq strxfrm("Mixed-casestring"); | |
922 | print "locale collation ignores hyphens\n" | |
923 | if $xfrm_string eq strxfrm("Mixedcase string"); | |
924 | print "locale collation ignores case\n" | |
925 | if $xfrm_string eq strxfrm("mixed-case string"); | |
926 | ||
39332f68 | 927 | C<strxfrm()> takes a string and maps it into a transformed string for use |
de108802 | 928 | in char-by-char comparisons against other transformed strings during |
14280422 | 929 | collation. "Under the hood", locale-affected Perl comparison operators |
39332f68 KW |
930 | call C<strxfrm()> for both operands, then do a char-by-char |
931 | comparison of the transformed strings. By calling C<strxfrm()> explicitly | |
14280422 | 932 | and using a non locale-affected comparison, the example attempts to save |
5a964f20 | 933 | a couple of transformations. But in fact, it doesn't save anything: Perl |
2ae324a7 | 934 | magic (see L<perlguts/Magic Variables>) creates the transformed version of a |
5a964f20 | 935 | string the first time it's needed in a comparison, then keeps this version around |
14280422 | 936 | in case it's needed again. An example rewritten the easy way with |
e38874e2 | 937 | C<cmp> runs just about as fast. It also copes with null characters |
39332f68 | 938 | embedded in strings; if you call C<strxfrm()> directly, it treats the first |
0c880285 | 939 | null it finds as a terminator. Don't expect the transformed strings |
5a964f20 | 940 | it produces to be portable across systems--or even from one revision |
39332f68 | 941 | of your operating system to the next. In short, don't call C<strxfrm()> |
e38874e2 | 942 | directly: let Perl do it for you. |
14280422 | 943 | |
5a964f20 | 944 | Note: C<use locale> isn't shown in some of these examples because it isn't |
dfcc8045 KW |
945 | needed: C<strcoll()> and C<strxfrm()> are POSIX functions |
946 | which use the standard system-supplied C<libc> functions that | |
947 | always obey the current C<LC_COLLATE> locale. | |
5f05dabc | 948 | |
cb88b78e | 949 | =head2 Category C<LC_CTYPE>: Character Types |
5f05dabc | 950 | |
d6ded950 KW |
951 | In the scope of a S<C<use locale>> form that includes C<LC_CTYPE>, Perl |
952 | obeys the C<LC_CTYPE> locale | |
14280422 | 953 | setting. This controls the application's notion of which characters are |
ebc3223b KW |
954 | alphabetic, numeric, punctuation, I<etc>. This affects Perl's C<\w> |
955 | regular expression metanotation, | |
f1cbbd6e | 956 | which stands for alphanumeric characters--that is, alphabetic, |
ebc3223b KW |
957 | numeric, and the platform's native underscore. |
958 | (Consult L<perlre> for more information about | |
14280422 | 959 | regular expressions.) Thanks to C<LC_CTYPE>, depending on your locale |
b4ffc3db TC |
960 | setting, characters like "E<aelig>", "E<eth>", "E<szlig>", and |
961 | "E<oslash>" may be understood as C<\w> characters. | |
ebc3223b KW |
962 | It also affects things like C<\s>, C<\D>, and the POSIX character |
963 | classes, like C<[[:graph:]]>. (See L<perlrecharclass> for more | |
964 | information on all these.) | |
5f05dabc | 965 | |
2c268ad5 | 966 | The C<LC_CTYPE> locale also provides the map used in transliterating |
68dc0745 | 967 | characters between lower and uppercase. This affects the case-mapping |
663d437a KW |
968 | functions--C<fc()>, C<lc()>, C<lcfirst()>, C<uc()>, and C<ucfirst()>; |
969 | case-mapping | |
b9cc4f69 | 970 | interpolation with C<\F>, C<\l>, C<\L>, C<\u>, or C<\U> in double-quoted |
26a9b33a | 971 | strings and C<s///> substitutions; and case-insensitive regular expression |
e38874e2 DD |
972 | pattern matching using the C<i> modifier. |
973 | ||
31f05a37 KW |
974 | Starting in v5.20, Perl supports UTF-8 locales for C<LC_CTYPE>, but |
975 | otherwise Perl only supports single-byte locales, such as the ISO 8859 | |
976 | series. This means that wide character locales, for example for Asian | |
b5eea289 KW |
977 | languages, are not well-supported. Use of these locales may cause core |
978 | dumps. If the platform has the capability for Perl to detect such a | |
979 | locale, starting in Perl v5.22, L<Perl will warn, default | |
980 | enabled|warnings/Category Hierarchy>, using the C<locale> warning | |
981 | category, whenever such a locale is switched into. The UTF-8 locale | |
982 | support is actually a | |
31f05a37 | 983 | superset of POSIX locales, because it is really full Unicode behavior |
13af4fd9 KW |
984 | as if no C<LC_CTYPE> locale were in effect at all (except for tainting; |
985 | see L</SECURITY>). POSIX locales, even UTF-8 ones, | |
31f05a37 KW |
986 | are lacking certain concepts in Unicode, such as the idea that changing |
987 | the case of a character could expand to be more than one character. | |
988 | Perl in a UTF-8 locale, will give you that expansion. Prior to v5.20, | |
989 | Perl treated a UTF-8 locale on some platforms like an ISO 8859-1 one, | |
990 | with some restrictions, and on other platforms more like the "C" locale. | |
991 | For releases v5.16 and v5.18, C<S<use locale 'not_characters>> could be | |
992 | used as a workaround for this (see L</Unicode and UTF-8>). | |
993 | ||
5d63e270 | 994 | Note that there are quite a few things that are unaffected by the |
663d437a KW |
995 | current locale. Any literal character is the native character for the |
996 | given platform. Hence 'A' means the character at code point 65 on ASCII | |
997 | platforms, and 193 on EBCDIC. That may or may not be an 'A' in the | |
998 | current locale, if that locale even has an 'A'. | |
999 | Similarly, all the escape sequences for particular characters, | |
5d63e270 KW |
1000 | C<\n> for example, always mean the platform's native one. This means, |
1001 | for example, that C<\N> in regular expressions (every character | |
1d2ab946 | 1002 | but new-line) works on the platform character set. |
5d63e270 | 1003 | |
8c6180a9 KW |
1004 | Starting in v5.22, Perl will by default warn when switching into a |
1005 | locale that redefines any ASCII printable character (plus C<\t> and | |
84035de0 KW |
1006 | C<\n>) into a different class than expected. This is likely to |
1007 | happen on modern locales only on EBCDIC platforms, where, for example, | |
1008 | a CCSID 0037 locale on a CCSID 1047 machine moves C<"[">, but it can | |
1009 | happen on ASCII platforms with the ISO 646 and other | |
8c6180a9 KW |
1010 | 7-bit locales that are essentially obsolete. Things may still work, |
1011 | depending on what features of Perl are used by the program. For | |
1012 | example, in the example from above where C<"|"> becomes a C<\w>, and | |
1013 | there are no regular expressions where this matters, the program may | |
1014 | still work properly. The warning lists all the characters that | |
1015 | it can determine could be adversely affected. | |
1016 | ||
14280422 DD |
1017 | B<Note:> A broken or malicious C<LC_CTYPE> locale definition may result |
1018 | in clearly ineligible characters being considered to be alphanumeric by | |
e199995e | 1019 | your application. For strict matching of (mundane) ASCII letters and |
5a964f20 | 1020 | digits--for example, in command strings--locale-aware applications |
5a0de581 | 1021 | should use C<\w> with the C</a> regular expression modifier. See L</"SECURITY">. |
5f05dabc | 1022 | |
fee33030 | 1023 | =head2 Category C<LC_NUMERIC>: Numeric Formatting |
5f05dabc | 1024 | |
d6ded950 KW |
1025 | After a proper C<POSIX::setlocale()> call, and within the scope of |
1026 | of a C<use locale> form that includes numerics, Perl obeys the | |
1027 | C<LC_NUMERIC> locale information, which controls an application's idea | |
1028 | of how numbers should be formatted for human readability. | |
b960a36e | 1029 | In most implementations the only effect is to |
b4ffc3db | 1030 | change the character used for the decimal point--perhaps from "." to ",". |
b960a36e | 1031 | The functions aren't aware of such niceties as thousands separation and |
5a0de581 | 1032 | so on. (See L</The localeconv function> if you care about these things.) |
5a964f20 | 1033 | |
b960a36e KW |
1034 | use POSIX qw(strtod setlocale LC_NUMERIC); |
1035 | use locale; | |
5f05dabc | 1036 | |
b960a36e | 1037 | setlocale LC_NUMERIC, ""; |
14280422 | 1038 | |
b960a36e | 1039 | $n = 5/2; # Assign numeric 2.5 to $n |
5f05dabc | 1040 | |
b960a36e | 1041 | $a = " $n"; # Locale-dependent conversion to string |
5f05dabc | 1042 | |
b960a36e | 1043 | print "half five is $n\n"; # Locale-dependent output |
5f05dabc | 1044 | |
b960a36e | 1045 | printf "half five is %g\n", $n; # Locale-dependent output |
5f05dabc | 1046 | |
b960a36e KW |
1047 | print "DECIMAL POINT IS COMMA\n" |
1048 | if $n == (strtod("2,5"))[0]; # Locale-dependent conversion | |
5f05dabc | 1049 | |
4bbcc6e8 JH |
1050 | See also L<I18N::Langinfo> and C<RADIXCHAR>. |
1051 | ||
cb88b78e | 1052 | =head2 Category C<LC_MONETARY>: Formatting of monetary amounts |
5f05dabc | 1053 | |
e199995e | 1054 | The C standard defines the C<LC_MONETARY> category, but not a function |
5a964f20 | 1055 | that is affected by its contents. (Those with experience of standards |
b0c42ed9 | 1056 | committees will recognize that the working group decided to punt on the |
fa9b773e KW |
1057 | issue.) Consequently, Perl essentially takes no notice of it. If you |
1058 | really want to use C<LC_MONETARY>, you can query its contents--see | |
5a0de581 | 1059 | L</The localeconv function>--and use the information that it returns in your |
e05ffc7d KW |
1060 | application's own formatting of currency amounts. However, you may well |
1061 | find that the information, voluminous and complex though it may be, still | |
1062 | does not quite meet your requirements: currency formatting is a hard nut | |
13a2d996 | 1063 | to crack. |
5f05dabc | 1064 | |
4bbcc6e8 JH |
1065 | See also L<I18N::Langinfo> and C<CRNCYSTR>. |
1066 | ||
ff52fcf1 | 1067 | =head2 Category C<LC_TIME>: Respresentation of time |
5f05dabc | 1068 | |
39332f68 | 1069 | Output produced by C<POSIX::strftime()>, which builds a formatted |
5f05dabc | 1070 | human-readable date/time string, is affected by the current C<LC_TIME> |
1071 | locale. Thus, in a French locale, the output produced by the C<%B> | |
1072 | format element (full month name) for the first month of the year would | |
5a964f20 | 1073 | be "janvier". Here's how to get a list of long month names in the |
5f05dabc | 1074 | current locale: |
1075 | ||
1076 | use POSIX qw(strftime); | |
14280422 DD |
1077 | for (0..11) { |
1078 | $long_month_name[$_] = | |
1079 | strftime("%B", 0, 0, 0, 1, $_, 96); | |
5f05dabc | 1080 | } |
1081 | ||
2619d284 KW |
1082 | Note: C<use locale> isn't needed in this example: C<strftime()> is a POSIX |
1083 | function which uses the standard system-supplied C<libc> function that | |
1084 | always obeys the current C<LC_TIME> locale. | |
5f05dabc | 1085 | |
4bbcc6e8 | 1086 | See also L<I18N::Langinfo> and C<ABDAY_1>..C<ABDAY_7>, C<DAY_1>..C<DAY_7>, |
2a2bf5f4 | 1087 | C<ABMON_1>..C<ABMON_12>, and C<ABMON_1>..C<ABMON_12>. |
4bbcc6e8 | 1088 | |
5f05dabc | 1089 | =head2 Other categories |
1090 | ||
2619d284 KW |
1091 | The remaining locale categories are not currently used by Perl itself. |
1092 | But again note that things Perl interacts with may use these, including | |
1093 | extensions outside the standard Perl distribution, and by the | |
98a6f11e | 1094 | operating system and its utilities. Note especially that the string |
1095 | value of C<$!> and the error messages given by external utilities may | |
1096 | be changed by C<LC_MESSAGES>. If you want to have portable error | |
265f5c4a | 1097 | codes, use C<%!>. See L<Errno>. |
14280422 DD |
1098 | |
1099 | =head1 SECURITY | |
1100 | ||
5a964f20 | 1101 | Although the main discussion of Perl security issues can be found in |
14280422 DD |
1102 | L<perlsec>, a discussion of Perl's locale handling would be incomplete |
1103 | if it did not draw your attention to locale-dependent security issues. | |
5a964f20 TC |
1104 | Locales--particularly on systems that allow unprivileged users to |
1105 | build their own locales--are untrustworthy. A malicious (or just plain | |
14280422 DD |
1106 | broken) locale can make a locale-aware application give unexpected |
1107 | results. Here are a few possibilities: | |
1108 | ||
1109 | =over 4 | |
1110 | ||
1111 | =item * | |
1112 | ||
1113 | Regular expression checks for safe file names or mail addresses using | |
5a964f20 | 1114 | C<\w> may be spoofed by an C<LC_CTYPE> locale that claims that |
dbf3c4d7 | 1115 | characters such as C<"E<gt>"> and C<"|"> are alphanumeric. |
14280422 DD |
1116 | |
1117 | =item * | |
1118 | ||
e38874e2 | 1119 | String interpolation with case-mapping, as in, say, C<$dest = |
cb88b78e | 1120 | "C:\U$name.$ext">, may produce dangerous results if a bogus C<LC_CTYPE> |
e38874e2 DD |
1121 | case-mapping table is in effect. |
1122 | ||
1123 | =item * | |
1124 | ||
14280422 DD |
1125 | A sneaky C<LC_COLLATE> locale could result in the names of students with |
1126 | "D" grades appearing ahead of those with "A"s. | |
1127 | ||
1128 | =item * | |
1129 | ||
5a964f20 | 1130 | An application that takes the trouble to use information in |
14280422 | 1131 | C<LC_MONETARY> may format debits as if they were credits and vice versa |
5a964f20 | 1132 | if that locale has been subverted. Or it might make payments in US |
14280422 DD |
1133 | dollars instead of Hong Kong dollars. |
1134 | ||
1135 | =item * | |
1136 | ||
39332f68 | 1137 | The date and day names in dates formatted by C<strftime()> could be |
14280422 | 1138 | manipulated to advantage by a malicious user able to subvert the |
5a964f20 | 1139 | C<LC_DATE> locale. ("Look--it says I wasn't in the building on |
14280422 DD |
1140 | Sunday.") |
1141 | ||
1142 | =back | |
1143 | ||
1144 | Such dangers are not peculiar to the locale system: any aspect of an | |
5a964f20 | 1145 | application's environment which may be modified maliciously presents |
14280422 | 1146 | similar challenges. Similarly, they are not specific to Perl: any |
5a964f20 | 1147 | programming language that allows you to write programs that take |
14280422 DD |
1148 | account of their environment exposes you to these issues. |
1149 | ||
5a964f20 TC |
1150 | Perl cannot protect you from all possibilities shown in the |
1151 | examples--there is no substitute for your own vigilance--but, when | |
14280422 | 1152 | C<use locale> is in effect, Perl uses the tainting mechanism (see |
5a964f20 | 1153 | L<perlsec>) to mark string results that become locale-dependent, and |
14280422 | 1154 | which may be untrustworthy in consequence. Here is a summary of the |
5a964f20 | 1155 | tainting behavior of operators and functions that may be affected by |
14280422 DD |
1156 | the locale: |
1157 | ||
1158 | =over 4 | |
1159 | ||
551e1d92 RB |
1160 | =item * |
1161 | ||
1162 | B<Comparison operators> (C<lt>, C<le>, C<ge>, C<gt> and C<cmp>): | |
14280422 DD |
1163 | |
1164 | Scalar true/false (or less/equal/greater) result is never tainted. | |
1165 | ||
551e1d92 RB |
1166 | =item * |
1167 | ||
1d2ab946 | 1168 | B<Case-mapping interpolation> (with C<\l>, C<\L>, C<\u>, C<\U>, or C<\F>) |
e38874e2 | 1169 | |
d6ded950 KW |
1170 | The result string containing interpolated material is tainted if |
1171 | a C<use locale> form that includes C<LC_CTYPE> is in effect. | |
e38874e2 | 1172 | |
551e1d92 RB |
1173 | =item * |
1174 | ||
1175 | B<Matching operator> (C<m//>): | |
14280422 DD |
1176 | |
1177 | Scalar true/false result never tainted. | |
1178 | ||
1d2ab946 | 1179 | All subpatterns, either delivered as a list-context result or as C<$1> |
d6ded950 KW |
1180 | I<etc>., are tainted if a C<use locale> form that includes |
1181 | C<LC_CTYPE> is in effect, and the subpattern | |
63baef57 KW |
1182 | regular expression contains a locale-dependent construct. These |
1183 | constructs include C<\w> (to match an alphanumeric character), C<\W> | |
1184 | (non-alphanumeric character), C<\b> and C<\B> (word-boundary and | |
1185 | non-boundardy, which depend on what C<\w> and C<\W> match), C<\s> | |
1186 | (whitespace character), C<\S> (non whitespace character), C<\d> and | |
1187 | C<\D> (digits and non-digits), and the POSIX character classes, such as | |
1188 | C<[:alpha:]> (see L<perlrecharclass/POSIX Character Classes>). | |
1189 | ||
1190 | Tainting is also likely if the pattern is to be matched | |
1191 | case-insensitively (via C</i>). The exception is if all the code points | |
1192 | to be matched this way are above 255 and do not have folds under Unicode | |
1193 | rules to below 256. Tainting is not done for these because Perl | |
1194 | only uses Unicode rules for such code points, and those rules are the | |
1195 | same no matter what the current locale. | |
1196 | ||
1d2ab946 KW |
1197 | The matched-pattern variables, C<$&>, C<$`> (pre-match), C<$'> |
1198 | (post-match), and C<$+> (last match) also are tainted. | |
14280422 | 1199 | |
551e1d92 RB |
1200 | =item * |
1201 | ||
1202 | B<Substitution operator> (C<s///>): | |
14280422 | 1203 | |
e38874e2 | 1204 | Has the same behavior as the match operator. Also, the left |
d6ded950 KW |
1205 | operand of C<=~> becomes tainted when a C<use locale> |
1206 | form that includes C<LC_CTYPE> is in effect, if modified as | |
66cbab2c | 1207 | a result of a substitution based on a regular |
1d2ab946 KW |
1208 | expression match involving any of the things mentioned in the previous |
1209 | item, or of case-mapping, such as C<\l>, C<\L>,C<\u>, C<\U>, or C<\F>. | |
14280422 | 1210 | |
551e1d92 RB |
1211 | =item * |
1212 | ||
39332f68 | 1213 | B<Output formatting functions> (C<printf()> and C<write()>): |
14280422 | 1214 | |
3cf03d68 JH |
1215 | Results are never tainted because otherwise even output from print, |
1216 | for example C<print(1/7)>, should be tainted if C<use locale> is in | |
1217 | effect. | |
14280422 | 1218 | |
551e1d92 RB |
1219 | =item * |
1220 | ||
39332f68 | 1221 | B<Case-mapping functions> (C<lc()>, C<lcfirst()>, C<uc()>, C<ucfirst()>): |
14280422 | 1222 | |
d6ded950 KW |
1223 | Results are tainted if a C<use locale> form that includes C<LC_CTYPE> is |
1224 | in effect. | |
14280422 | 1225 | |
551e1d92 RB |
1226 | =item * |
1227 | ||
39332f68 KW |
1228 | B<POSIX locale-dependent functions> (C<localeconv()>, C<strcoll()>, |
1229 | C<strftime()>, C<strxfrm()>): | |
14280422 DD |
1230 | |
1231 | Results are never tainted. | |
1232 | ||
14280422 DD |
1233 | =back |
1234 | ||
1235 | Three examples illustrate locale-dependent tainting. | |
1236 | The first program, which ignores its locale, won't run: a value taken | |
54310121 | 1237 | directly from the command line may not be used to name an output file |
14280422 DD |
1238 | when taint checks are enabled. |
1239 | ||
1240 | #/usr/local/bin/perl -T | |
1241 | # Run with taint checking | |
1242 | ||
54310121 | 1243 | # Command line sanity check omitted... |
14280422 DD |
1244 | $tainted_output_file = shift; |
1245 | ||
1246 | open(F, ">$tainted_output_file") | |
3183d96c | 1247 | or warn "Open of $tainted_output_file failed: $!\n"; |
14280422 DD |
1248 | |
1249 | The program can be made to run by "laundering" the tainted value through | |
5a964f20 TC |
1250 | a regular expression: the second example--which still ignores locale |
1251 | information--runs, creating the file named on its command line | |
14280422 DD |
1252 | if it can. |
1253 | ||
1254 | #/usr/local/bin/perl -T | |
1255 | ||
1256 | $tainted_output_file = shift; | |
1257 | $tainted_output_file =~ m%[\w/]+%; | |
1258 | $untainted_output_file = $&; | |
1259 | ||
1260 | open(F, ">$untainted_output_file") | |
1261 | or warn "Open of $untainted_output_file failed: $!\n"; | |
1262 | ||
5a964f20 | 1263 | Compare this with a similar but locale-aware program: |
14280422 DD |
1264 | |
1265 | #/usr/local/bin/perl -T | |
1266 | ||
1267 | $tainted_output_file = shift; | |
1268 | use locale; | |
1269 | $tainted_output_file =~ m%[\w/]+%; | |
1270 | $localized_output_file = $&; | |
1271 | ||
1272 | open(F, ">$localized_output_file") | |
1273 | or warn "Open of $localized_output_file failed: $!\n"; | |
1274 | ||
1d2ab946 | 1275 | This third program fails to run because C<$&> is tainted: it is the result |
5a964f20 | 1276 | of a match involving C<\w> while C<use locale> is in effect. |
5f05dabc | 1277 | |
1278 | =head1 ENVIRONMENT | |
1279 | ||
1280 | =over 12 | |
1281 | ||
ee1ec05f KW |
1282 | =item PERL_SKIP_LOCALE_INIT |
1283 | ||
c5c88224 KW |
1284 | This environment variable, available starting in Perl v5.20, if set |
1285 | (to any value), tells Perl to not use the rest of the | |
ee1ec05f KW |
1286 | environment variables to initialize with. Instead, Perl uses whatever |
1287 | the current locale settings are. This is particularly useful in | |
1288 | embedded environments, see | |
1289 | L<perlembed/Using embedded Perl with POSIX locales>. | |
1290 | ||
5f05dabc | 1291 | =item PERL_BADLANG |
1292 | ||
14280422 | 1293 | A string that can suppress Perl's warning about failed locale settings |
54310121 | 1294 | at startup. Failure can occur if the locale support in the operating |
5a964f20 | 1295 | system is lacking (broken) in some way--or if you mistyped the name of |
900bd440 | 1296 | a locale when you set up your environment. If this environment |
22ff3130 HS |
1297 | variable is absent, or has a value other than "0" or "", Perl will |
1298 | complain about locale setting failures. | |
5f05dabc | 1299 | |
cb88b78e | 1300 | B<NOTE>: C<PERL_BADLANG> only gives you a way to hide the warning message. |
14280422 DD |
1301 | The message tells about some problem in your system's locale support, |
1302 | and you should investigate what the problem is. | |
5f05dabc | 1303 | |
1304 | =back | |
1305 | ||
1306 | The following environment variables are not specific to Perl: They are | |
39332f68 | 1307 | part of the standardized (ISO C, XPG4, POSIX 1.c) C<setlocale()> method |
b385bb4d KW |
1308 | for controlling an application's opinion on data. Windows is non-POSIX, |
1309 | but Perl arranges for the following to work as described anyway. | |
65ebb059 KW |
1310 | If the locale given by an environment variable is not valid, Perl tries |
1311 | the next lower one in priority. If none are valid, on Windows, the | |
1312 | system default locale is then tried. If all else fails, the C<"C"> | |
1313 | locale is used. If even that doesn't work, something is badly broken, | |
c5e9a8e7 | 1314 | but Perl tries to forge ahead with whatever the locale settings might |
65ebb059 | 1315 | be. |
5f05dabc | 1316 | |
1317 | =over 12 | |
1318 | ||
cb88b78e | 1319 | =item C<LC_ALL> |
5f05dabc | 1320 | |
5a964f20 | 1321 | C<LC_ALL> is the "override-all" locale environment variable. If |
5f05dabc | 1322 | set, it overrides all the rest of the locale environment variables. |
1323 | ||
cb88b78e | 1324 | =item C<LANGUAGE> |
528d65ad JH |
1325 | |
1326 | B<NOTE>: C<LANGUAGE> is a GNU extension, it affects you only if you | |
1327 | are using the GNU libc. This is the case if you are using e.g. Linux. | |
e1020413 | 1328 | If you are using "commercial" Unixes you are most probably I<not> |
22b6f60d JH |
1329 | using GNU libc and you can ignore C<LANGUAGE>. |
1330 | ||
1331 | However, in the case you are using C<LANGUAGE>: it affects the | |
1332 | language of informational, warning, and error messages output by | |
1333 | commands (in other words, it's like C<LC_MESSAGES>) but it has higher | |
96090e4f | 1334 | priority than C<LC_ALL>. Moreover, it's not a single value but |
22b6f60d JH |
1335 | instead a "path" (":"-separated list) of I<languages> (not locales). |
1336 | See the GNU C<gettext> library documentation for more information. | |
528d65ad | 1337 | |
3ee1a09c | 1338 | =item C<LC_CTYPE> |
5f05dabc | 1339 | |
1340 | In the absence of C<LC_ALL>, C<LC_CTYPE> chooses the character type | |
1341 | locale. In the absence of both C<LC_ALL> and C<LC_CTYPE>, C<LANG> | |
1342 | chooses the character type locale. | |
1343 | ||
cb88b78e | 1344 | =item C<LC_COLLATE> |
5f05dabc | 1345 | |
14280422 DD |
1346 | In the absence of C<LC_ALL>, C<LC_COLLATE> chooses the collation |
1347 | (sorting) locale. In the absence of both C<LC_ALL> and C<LC_COLLATE>, | |
1348 | C<LANG> chooses the collation locale. | |
5f05dabc | 1349 | |
cb88b78e | 1350 | =item C<LC_MONETARY> |
5f05dabc | 1351 | |
14280422 DD |
1352 | In the absence of C<LC_ALL>, C<LC_MONETARY> chooses the monetary |
1353 | formatting locale. In the absence of both C<LC_ALL> and C<LC_MONETARY>, | |
1354 | C<LANG> chooses the monetary formatting locale. | |
5f05dabc | 1355 | |
cb88b78e | 1356 | =item C<LC_NUMERIC> |
5f05dabc | 1357 | |
1358 | In the absence of C<LC_ALL>, C<LC_NUMERIC> chooses the numeric format | |
1359 | locale. In the absence of both C<LC_ALL> and C<LC_NUMERIC>, C<LANG> | |
1360 | chooses the numeric format. | |
1361 | ||
cb88b78e | 1362 | =item C<LC_TIME> |
5f05dabc | 1363 | |
14280422 DD |
1364 | In the absence of C<LC_ALL>, C<LC_TIME> chooses the date and time |
1365 | formatting locale. In the absence of both C<LC_ALL> and C<LC_TIME>, | |
1366 | C<LANG> chooses the date and time formatting locale. | |
5f05dabc | 1367 | |
cb88b78e | 1368 | =item C<LANG> |
5f05dabc | 1369 | |
14280422 DD |
1370 | C<LANG> is the "catch-all" locale environment variable. If it is set, it |
1371 | is used as the last resort after the overall C<LC_ALL> and the | |
3ee1a09c | 1372 | category-specific C<LC_I<foo>>. |
5f05dabc | 1373 | |
1374 | =back | |
1375 | ||
7e4353e9 RGS |
1376 | =head2 Examples |
1377 | ||
cb88b78e | 1378 | The C<LC_NUMERIC> controls the numeric output: |
7e4353e9 | 1379 | |
ef3087ec KW |
1380 | use locale; |
1381 | use POSIX qw(locale_h); # Imports setlocale() and the LC_ constants. | |
1382 | setlocale(LC_NUMERIC, "fr_FR") or die "Pardon"; | |
1383 | printf "%g\n", 1.23; # If the "fr_FR" succeeded, probably shows 1,23. | |
7e4353e9 | 1384 | |
39332f68 | 1385 | and also how strings are parsed by C<POSIX::strtod()> as numbers: |
7e4353e9 | 1386 | |
ef3087ec KW |
1387 | use locale; |
1388 | use POSIX qw(locale_h strtod); | |
1389 | setlocale(LC_NUMERIC, "de_DE") or die "Entschuldigung"; | |
1390 | my $x = strtod("2,34") + 5; | |
1391 | print $x, "\n"; # Probably shows 7,34. | |
7e4353e9 | 1392 | |
5f05dabc | 1393 | =head1 NOTES |
1394 | ||
b960a36e KW |
1395 | =head2 String C<eval> and C<LC_NUMERIC> |
1396 | ||
1397 | A string L<eval|perlfunc/eval EXPR> parses its expression as standard | |
1398 | Perl. It is therefore expecting the decimal point to be a dot. If | |
1399 | C<LC_NUMERIC> is set to have this be a comma instead, the parsing will | |
1400 | be confused, perhaps silently. | |
1401 | ||
1402 | use locale; | |
1403 | use POSIX qw(locale_h); | |
1404 | setlocale(LC_NUMERIC, "fr_FR") or die "Pardon"; | |
1405 | my $a = 1.2; | |
1406 | print eval "$a + 1.5"; | |
1407 | print "\n"; | |
1408 | ||
1409 | prints C<13,5>. This is because in that locale, the comma is the | |
1410 | decimal point character. The C<eval> thus expands to: | |
1411 | ||
1412 | eval "1,2 + 1.5" | |
1413 | ||
1414 | and the result is not what you likely expected. No warnings are | |
1415 | generated. If you do string C<eval>'s within the scope of | |
1416 | S<C<use locale>>, you should instead change the C<eval> line to do | |
1417 | something like: | |
1418 | ||
1419 | print eval "no locale; $a + 1.5"; | |
1420 | ||
1421 | This prints C<2.7>. | |
1422 | ||
d6ded950 KW |
1423 | You could also exclude C<LC_NUMERIC>, if you don't need it, by |
1424 | ||
1425 | use locale ':!numeric'; | |
1426 | ||
5f05dabc | 1427 | =head2 Backward compatibility |
1428 | ||
b0c42ed9 | 1429 | Versions of Perl prior to 5.004 B<mostly> ignored locale information, |
5a964f20 TC |
1430 | generally behaving as if something similar to the C<"C"> locale were |
1431 | always in force, even if the program environment suggested otherwise | |
5a0de581 | 1432 | (see L</The setlocale function>). By default, Perl still behaves this |
5a964f20 TC |
1433 | way for backward compatibility. If you want a Perl application to pay |
1434 | attention to locale information, you B<must> use the S<C<use locale>> | |
5a0de581 | 1435 | pragma (see L</The "use locale" pragma>) or, in the unlikely event |
062ca197 | 1436 | that you want to do so for just pattern matching, the |
70709c68 KW |
1437 | C</l> regular expression modifier (see L<perlre/Character set |
1438 | modifiers>) to instruct it to do so. | |
b0c42ed9 JH |
1439 | |
1440 | Versions of Perl from 5.002 to 5.003 did use the C<LC_CTYPE> | |
5a964f20 TC |
1441 | information if available; that is, C<\w> did understand what |
1442 | were the letters according to the locale environment variables. | |
b0c42ed9 JH |
1443 | The problem was that the user had no control over the feature: |
1444 | if the C library supported locales, Perl used them. | |
1445 | ||
1446 | =head2 I18N:Collate obsolete | |
1447 | ||
5a964f20 | 1448 | In versions of Perl prior to 5.004, per-locale collation was possible |
b0c42ed9 JH |
1449 | using the C<I18N::Collate> library module. This module is now mildly |
1450 | obsolete and should be avoided in new applications. The C<LC_COLLATE> | |
1451 | functionality is now integrated into the Perl core language: One can | |
1452 | use locale-specific scalar data completely normally with C<use locale>, | |
1453 | so there is no longer any need to juggle with the scalar references of | |
1454 | C<I18N::Collate>. | |
5f05dabc | 1455 | |
14280422 | 1456 | =head2 Sort speed and memory use impacts |
5f05dabc | 1457 | |
1458 | Comparing and sorting by locale is usually slower than the default | |
14280422 DD |
1459 | sorting; slow-downs of two to four times have been observed. It will |
1460 | also consume more memory: once a Perl scalar variable has participated | |
1461 | in any string comparison or sorting operation obeying the locale | |
1462 | collation rules, it will take 3-15 times more memory than before. (The | |
1463 | exact multiplier depends on the string's contents, the operating system | |
1464 | and the locale.) These downsides are dictated more by the operating | |
1465 | system's implementation of the locale system than by Perl. | |
5f05dabc | 1466 | |
5f05dabc | 1467 | =head2 Freely available locale definitions |
1468 | ||
66cbab2c KW |
1469 | The Unicode CLDR project extracts the POSIX portion of many of its |
1470 | locales, available at | |
1471 | ||
e784ce68 KW |
1472 | http://unicode.org/Public/cldr/2.0.1/ |
1473 | ||
1474 | (Newer versions of CLDR require you to compute the POSIX data yourself. | |
1475 | See L<http://unicode.org/Public/cldr/latest/>.) | |
66cbab2c | 1476 | |
08d7a6b2 LB |
1477 | There is a large collection of locale definitions at: |
1478 | ||
1479 | http://std.dkuug.dk/i18n/WG15-collection/locales/ | |
1480 | ||
1481 | You should be aware that it is | |
14280422 | 1482 | unsupported, and is not claimed to be fit for any purpose. If your |
5a964f20 | 1483 | system allows installation of arbitrary locales, you may find the |
14280422 DD |
1484 | definitions useful as they are, or as a basis for the development of |
1485 | your own locales. | |
5f05dabc | 1486 | |
14280422 | 1487 | =head2 I18n and l10n |
5f05dabc | 1488 | |
b0c42ed9 JH |
1489 | "Internationalization" is often abbreviated as B<i18n> because its first |
1490 | and last letters are separated by eighteen others. (You may guess why | |
1491 | the internalin ... internaliti ... i18n tends to get abbreviated.) In | |
1492 | the same way, "localization" is often abbreviated to B<l10n>. | |
14280422 DD |
1493 | |
1494 | =head2 An imperfect standard | |
1495 | ||
1496 | Internationalization, as defined in the C and POSIX standards, can be | |
e9bc6d6b KW |
1497 | criticized as incomplete and ungainly. They also have a tendency, like |
1498 | standards groups, to divide the world into nations, when we all know | |
1499 | that the world can equally well be divided into bankers, bikers, gamers, | |
1500 | and so on. | |
5f05dabc | 1501 | |
b310b053 JH |
1502 | =head1 Unicode and UTF-8 |
1503 | ||
7ee2ae1e | 1504 | The support of Unicode is new starting from Perl version v5.6, and more fully |
31f05a37 KW |
1505 | implemented in versions v5.8 and later. See L<perluniintro>. |
1506 | ||
a4a439fb KW |
1507 | Starting in Perl v5.20, UTF-8 locales are supported in Perl, except |
1508 | C<LC_COLLATE> is only partially supported; collation support is improved | |
1509 | in Perl v5.26 to a level that may be sufficient for your needs | |
1510 | (see L</Category C<LC_COLLATE>: Collation: Text Comparisons and Sorting>). | |
1511 | ||
1512 | If you have Perl v5.16 or v5.18 and can't upgrade, you can use | |
66cbab2c KW |
1513 | |
1514 | use locale ':not_characters'; | |
1515 | ||
1516 | When this form of the pragma is used, only the non-character portions of | |
1517 | locales are used by Perl, for example C<LC_NUMERIC>. Perl assumes that | |
1518 | you have translated all the characters it is to operate on into Unicode | |
1519 | (actually the platform's native character set (ASCII or EBCDIC) plus | |
1520 | Unicode). For data in files, this can conveniently be done by also | |
1521 | specifying | |
1522 | ||
1523 | use open ':locale'; | |
1524 | ||
1525 | This pragma arranges for all inputs from files to be translated into | |
1526 | Unicode from the current locale as specified in the environment (see | |
1527 | L</ENVIRONMENT>), and all outputs to files to be translated back | |
1528 | into the locale. (See L<open>). On a per-filehandle basis, you can | |
1529 | instead use the L<PerlIO::locale> module, or the L<Encode::Locale> | |
1530 | module, both available from CPAN. The latter module also has methods to | |
1531 | ease the handling of C<ARGV> and environment variables, and can be used | |
31f05a37 | 1532 | on individual strings. If you know that all your locales will be |
66cbab2c KW |
1533 | UTF-8, as many are these days, you can use the L<B<-C>|perlrun/-C> |
1534 | command line switch. | |
1535 | ||
1536 | This form of the pragma allows essentially seamless handling of locales | |
31f05a37 | 1537 | with Unicode. The collation order will be by Unicode code point order. |
a4a439fb | 1538 | L<Unicode::Collate> can be used to get Unicode rules collation. |
66cbab2c | 1539 | |
31f05a37 KW |
1540 | All the modules and switches just described can be used in v5.20 with |
1541 | just plain C<use locale>, and, should the input locales not be UTF-8, | |
1542 | you'll get the less than ideal behavior, described below, that you get | |
1543 | with pre-v5.16 Perls, or when you use the locale pragma without the | |
1544 | C<:not_characters> parameter in v5.16 and v5.18. If you are using | |
1545 | exclusively UTF-8 locales in v5.20 and higher, the rest of this section | |
1546 | does not apply to you. | |
1547 | ||
1548 | There are two cases, multi-byte and single-byte locales. First | |
1549 | multi-byte: | |
1550 | ||
1551 | The only multi-byte (or wide character) locale that Perl is ever likely | |
1552 | to support is UTF-8. This is due to the difficulty of implementation, | |
1553 | the fact that high quality UTF-8 locales are now published for every | |
e784ce68 KW |
1554 | area of the world (L<http://unicode.org/Public/cldr/2.0.1/> for |
1555 | ones that are already set-up, but from an earlier version; | |
1556 | L<http://unicode.org/Public/cldr/latest/> for the most up-to-date, but | |
1557 | you have to extract the POSIX information yourself), and that | |
31f05a37 KW |
1558 | failing all that you can use the L<Encode> module to translate to/from |
1559 | your locale. So, you'll have to do one of those things if you're using | |
1560 | one of these locales, such as Big5 or Shift JIS. For UTF-8 locales, in | |
1561 | Perls (pre v5.20) that don't have full UTF-8 locale support, they may | |
1562 | work reasonably well (depending on your C library implementation) | |
1563 | simply because both | |
dc4bfc4b KW |
1564 | they and Perl store characters that take up multiple bytes the same way. |
1565 | However, some, if not most, C library implementations may not process | |
1566 | the characters in the upper half of the Latin-1 range (128 - 255) | |
cb88b78e | 1567 | properly under C<LC_CTYPE>. To see if a character is a particular type |
dc4bfc4b KW |
1568 | under a locale, Perl uses the functions like C<isalnum()>. Your C |
1569 | library may not work for UTF-8 locales with those functions, instead | |
dbf3c4d7 KW |
1570 | only working under the newer wide library functions like C<iswalnum()>, |
1571 | which Perl does not use. | |
1572 | These multi-byte locales are treated like single-byte locales, and will | |
1573 | have the restrictions described below. Starting in Perl v5.22 a warning | |
1574 | message is raised when Perl detects a multi-byte locale that it doesn't | |
1575 | fully support. | |
e199995e | 1576 | |
31f05a37 | 1577 | For single-byte locales, |
e199995e | 1578 | Perl generally takes the tack to use locale rules on code points that can fit |
66cbab2c KW |
1579 | in a single byte, and Unicode rules for those that can't (though this |
1580 | isn't uniformly applied, see the note at the end of this section). This | |
1581 | prevents many problems in locales that aren't UTF-8. Suppose the locale | |
1582 | is ISO8859-7, Greek. The character at 0xD7 there is a capital Chi. But | |
1583 | in the ISO8859-1 locale, Latin1, it is a multiplication sign. The POSIX | |
1584 | regular expression character class C<[[:alpha:]]> will magically match | |
1585 | 0xD7 in the Greek locale but not in the Latin one. | |
e199995e | 1586 | |
1d2ab946 | 1587 | However, there are places where this breaks down. Certain Perl constructs are |
b4ffc3db TC |
1588 | for Unicode only, such as C<\p{Alpha}>. They assume that 0xD7 always has its |
1589 | Unicode meaning (or the equivalent on EBCDIC platforms). Since Latin1 is a | |
1590 | subset of Unicode and 0xD7 is the multiplication sign in both Latin1 and | |
1591 | Unicode, C<\p{Alpha}> will never match it, regardless of locale. A similar | |
0c880285 | 1592 | issue occurs with C<\N{...}>. Prior to v5.20, it is therefore a bad |
31f05a37 | 1593 | idea to use C<\p{}> or |
66cbab2c | 1594 | C<\N{}> under plain C<use locale>--I<unless> you can guarantee that the |
dbf3c4d7 | 1595 | locale will be ISO8859-1. Use POSIX character classes instead. |
66cbab2c KW |
1596 | |
1597 | Another problem with this approach is that operations that cross the | |
1598 | single byte/multiple byte boundary are not well-defined, and so are | |
4a70680a | 1599 | disallowed. (This boundary is between the codepoints at 255/256.) |
66cbab2c KW |
1600 | For example, lower casing LATIN CAPITAL LETTER Y WITH DIAERESIS (U+0178) |
1601 | should return LATIN SMALL LETTER Y WITH DIAERESIS (U+00FF). But in the | |
1602 | Greek locale, for example, there is no character at 0xFF, and Perl | |
1603 | has no way of knowing what the character at 0xFF is really supposed to | |
1604 | represent. Thus it disallows the operation. In this mode, the | |
1605 | lowercase of U+0178 is itself. | |
1606 | ||
1607 | The same problems ensue if you enable automatic UTF-8-ification of your | |
e199995e | 1608 | standard file handles, default C<open()> layer, and C<@ARGV> on non-ISO8859-1, |
b4ffc3db TC |
1609 | non-UTF-8 locales (by using either the B<-C> command line switch or the |
1610 | C<PERL_UNICODE> environment variable; see L<perlrun>). | |
1611 | Things are read in as UTF-8, which would normally imply a Unicode | |
1612 | interpretation, but the presence of a locale causes them to be interpreted | |
1613 | in that locale instead. For example, a 0xD7 code point in the Unicode | |
1614 | input, which should mean the multiplication sign, won't be interpreted by | |
66cbab2c | 1615 | Perl that way under the Greek locale. This is not a problem |
b4ffc3db | 1616 | I<provided> you make certain that all locales will always and only be either |
66cbab2c | 1617 | an ISO8859-1, or, if you don't have a deficient C library, a UTF-8 locale. |
b4ffc3db | 1618 | |
1d2ab946 KW |
1619 | Still another problem is that this approach can lead to two code |
1620 | points meaning the same character. Thus in a Greek locale, both U+03A7 | |
1621 | and U+00D7 are GREEK CAPITAL LETTER CHI. | |
1622 | ||
613abc6d KW |
1623 | Because of all these problems, starting in v5.22, Perl will raise a |
1624 | warning if a multi-byte (hence Unicode) code point is used when a | |
1625 | single-byte locale is in effect. (Although it doesn't check for this if | |
1626 | doing so would unreasonably slow execution down.) | |
1627 | ||
b4ffc3db TC |
1628 | Vendor locales are notoriously buggy, and it is difficult for Perl to test |
1629 | its locale-handling code because this interacts with code that Perl has no | |
1630 | control over; therefore the locale-handling code in Perl may be buggy as | |
66cbab2c KW |
1631 | well. (However, the Unicode-supplied locales should be better, and |
1632 | there is a feed back mechanism to correct any problems. See | |
1633 | L</Freely available locale definitions>.) | |
1634 | ||
7ee2ae1e | 1635 | If you have Perl v5.16, the problems mentioned above go away if you use |
66cbab2c | 1636 | the C<:not_characters> parameter to the locale pragma (except for vendor |
7ee2ae1e | 1637 | bugs in the non-character portions). If you don't have v5.16, and you |
66cbab2c KW |
1638 | I<do> have locales that work, using them may be worthwhile for certain |
1639 | specific purposes, as long as you keep in mind the gotchas already | |
1640 | mentioned. For example, if the collation for your locales works, it | |
1641 | runs faster under locales than under L<Unicode::Collate>; and you gain | |
1642 | access to such things as the local currency symbol and the names of the | |
7ee2ae1e | 1643 | months and days of the week. (But to hammer home the point, in v5.16, |
66cbab2c KW |
1644 | you get this access without the downsides of locales by using the |
1645 | C<:not_characters> form of the pragma.) | |
1646 | ||
1647 | Note: The policy of using locale rules for code points that can fit in a | |
1648 | byte, and Unicode rules for those that can't is not uniformly applied. | |
7ee2ae1e | 1649 | Pre-v5.12, it was somewhat haphazard; in v5.12 it was applied fairly |
66cbab2c | 1650 | consistently to regular expression matching except for bracketed |
7ee2ae1e | 1651 | character classes; in v5.14 it was extended to all regex matches; and in |
663d437a | 1652 | v5.16 to the casing operations such as C<\L> and C<uc()>. For |
dbf3c4d7 | 1653 | collation, in all releases so far, the system's C<strxfrm()> function is |
a4a439fb KW |
1654 | called, and whatever it does is what you get. Starting in v5.26, various |
1655 | bugs are fixed with the way perl uses this function. | |
b310b053 | 1656 | |
5f05dabc | 1657 | =head1 BUGS |
1658 | ||
4e615abd KW |
1659 | =head2 Collation of strings containing embedded C<NUL> characters |
1660 | ||
6696cfa7 KW |
1661 | C<NUL> characters will sort the same as the lowest collating control |
1662 | character does, or to C<"\001"> in the unlikely event that there are no | |
1663 | control characters at all in the locale. In cases where the strings | |
1664 | don't contain this non-C<NUL> control, the results will be correct, and | |
1665 | in many locales, this control, whatever it might be, will rarely be | |
1666 | encountered. But there are cases where a C<NUL> should sort before this | |
1667 | control, but doesn't. If two strings do collate identically, the one | |
0c880285 KW |
1668 | containing the C<NUL> will sort to earlier. Prior to 5.26, there were |
1669 | more bugs. | |
4e615abd | 1670 | |
e9bc6d6b KW |
1671 | =head2 Multi-threaded |
1672 | ||
1673 | XS code or C-language libraries called from it that use the system | |
1674 | L<C<setlocale(3)>> function (except on Windows) likely will not work | |
1675 | from a multi-threaded application without changes. See | |
1676 | L<perlxs/Locale-aware XS code>. | |
1677 | ||
1678 | An XS module that is locale-dependent could have been written under the | |
1679 | assumption that it will never be called in a multi-threaded environment, | |
1680 | and so uses other non-locale constructs that aren't multi-thread-safe. | |
1681 | See L<perlxs/Thread-aware system interfaces>. | |
1682 | ||
1683 | POSIX does not define a way to get the name of the current per-thread | |
1684 | locale. Some systems, such as Darwin and NetBSD do implement a | |
1685 | function, L<querylocale(3)> to do this. On non-Windows systems without | |
1686 | it, such as Linux, there are some additional caveats: | |
1687 | ||
1688 | =over | |
1689 | ||
1690 | =item * | |
1691 | ||
1692 | An embedded perl needs to be started up while the global locale is in | |
1693 | effect. See L<perlembed/Using embedded Perl with POSIX locales>. | |
1694 | ||
1695 | =item * | |
1696 | ||
1697 | It becomes more important for perl to know about all the possible | |
1698 | locale categories on the platform, even if they aren't apparently used | |
1699 | in your program. Perl knows all of the Linux ones. If your platform | |
1700 | has others, you can send email to L<mailto:perlbug@perl.org> for | |
1701 | inclusion of it in the next release. In the meantime, it is possible to | |
1702 | edit the Perl source to teach it about the category, and then recompile. | |
1703 | Search for instances of, say, C<LC_PAPER> in the source, and use that as | |
1704 | a template to add the omitted one. | |
1705 | ||
1706 | =item * | |
1707 | ||
1708 | It is possible, though hard to do, to call C<POSIX::setlocale> with a | |
1709 | locale that it doesn't recognize as syntactically legal, but actually is | |
1710 | legal on that system. This should happen only with embedded perls, or | |
1711 | if you hand-craft a locale name yourself. | |
1712 | ||
1713 | =back | |
1714 | ||
5f05dabc | 1715 | =head2 Broken systems |
1716 | ||
5a964f20 | 1717 | In certain systems, the operating system's locale support |
2bdf8add | 1718 | is broken and cannot be fixed or used by Perl. Such deficiencies can |
b4ffc3db | 1719 | and will result in mysterious hangs and/or Perl core dumps when |
2bdf8add | 1720 | C<use locale> is in effect. When confronted with such a system, |
7f2de2d2 | 1721 | please report in excruciating detail to <F<perlbug@perl.org>>, and |
b4ffc3db | 1722 | also contact your vendor: bug fixes may exist for these problems |
2bdf8add | 1723 | in your operating system. Sometimes such bug fixes are called an |
83fb1bf0 KW |
1724 | operating system upgrade. If you have the source for Perl, include in |
1725 | the perlbug email the output of the test described above in L</Testing | |
1726 | for broken locales>. | |
5f05dabc | 1727 | |
1728 | =head1 SEE ALSO | |
1729 | ||
b310b053 | 1730 | L<I18N::Langinfo>, L<perluniintro>, L<perlunicode>, L<open>, |
106ab961 | 1731 | L<POSIX/localeconv>, |
4bbcc6e8 JH |
1732 | L<POSIX/setlocale>, L<POSIX/strcoll>, L<POSIX/strftime>, |
1733 | L<POSIX/strtod>, L<POSIX/strxfrm>. | |
5f05dabc | 1734 | |
ccd65d51 KW |
1735 | For special considerations when Perl is embedded in a C program, |
1736 | see L<perlembed/Using embedded Perl with POSIX locales>. | |
1737 | ||
5f05dabc | 1738 | =head1 HISTORY |
1739 | ||
b0c42ed9 | 1740 | Jarkko Hietaniemi's original F<perli18n.pod> heavily hacked by Dominic |
5a964f20 | 1741 | Dunlop, assisted by the perl5-porters. Prose worked over a bit by |
106ab961 | 1742 | Tom Christiansen, and now maintained by Perl 5 porters. |