Commit | Line | Data |
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8990e307 LW |
1 | package Exporter; |
2 | ||
748a9306 | 3 | require 5.001; |
8990e307 | 4 | |
a0d0e21e | 5 | $ExportLevel = 0; |
4af1b167 | 6 | $Verbose ||= 0; |
90564d98 | 7 | $VERSION = '5.562'; |
2b5b2650 | 8 | |
4af1b167 IZ |
9 | sub export_to_level { |
10 | require Exporter::Heavy; | |
11 | goto &heavy_export_to_level; | |
84902520 TB |
12 | } |
13 | ||
4af1b167 IZ |
14 | sub export { |
15 | require Exporter::Heavy; | |
16 | goto &heavy_export; | |
748a9306 LW |
17 | } |
18 | ||
4af1b167 IZ |
19 | sub export_tags { |
20 | require Exporter::Heavy; | |
21 | _push_tags((caller)[0], "EXPORT", \@_); | |
2b5b2650 | 22 | } |
23 | ||
4af1b167 IZ |
24 | sub export_ok_tags { |
25 | require Exporter::Heavy; | |
26 | _push_tags((caller)[0], "EXPORT_OK", \@_); | |
a0d0e21e LW |
27 | } |
28 | ||
4af1b167 IZ |
29 | sub import { |
30 | my $pkg = shift; | |
31 | my $callpkg = caller($ExportLevel); | |
32 | *exports = *{"$pkg\::EXPORT"}; | |
33 | # We *need* to treat @{"$pkg\::EXPORT_FAIL"} since Carp uses it :-( | |
34 | *fail = *{"$pkg\::EXPORT_FAIL"}; | |
35 | return export $pkg, $callpkg, @_ | |
36 | if $Verbose or $Debug or @fail > 1; | |
37 | my $args = @_ or @_ = @exports; | |
38 | ||
39 | if ($args and not %exports) { | |
40 | foreach my $sym (@exports, @{"$pkg\::EXPORT_OK"}) { | |
41 | $sym =~ s/^&//; | |
42 | $exports{$sym} = 1; | |
3221d3b0 | 43 | } |
4af1b167 IZ |
44 | } |
45 | if ($Verbose or $Debug | |
46 | or grep {/\W/ or $args and not exists $exports{$_} | |
47 | or @fail and $_ eq $fail[0] | |
48 | or (@{"$pkg\::EXPORT_OK"} | |
49 | and $_ eq ${"$pkg\::EXPORT_OK"}[0])} @_) { | |
50 | return export $pkg, $callpkg, ($args ? @_ : ()); | |
51 | } | |
52 | #local $SIG{__WARN__} = sub {require Carp; goto &Carp::carp}; | |
53 | local $SIG{__WARN__} = | |
54 | sub {require Carp; local $Carp::CarpLevel = 1; &Carp::carp}; | |
55 | foreach $sym (@_) { | |
56 | # shortcut for the common case of no type character | |
57 | *{"$callpkg\::$sym"} = \&{"$pkg\::$sym"}; | |
58 | } | |
e50aee73 AD |
59 | } |
60 | ||
8990e307 | 61 | 1; |
2b5b2650 | 62 | |
63 | # A simple self test harness. Change 'require Carp' to 'use Carp ()' for testing. | |
64 | # package main; eval(join('',<DATA>)) or die $@ unless caller; | |
65 | __END__ | |
66 | package Test; | |
67 | $INC{'Exporter.pm'} = 1; | |
68 | @ISA = qw(Exporter); | |
69 | @EXPORT = qw(A1 A2 A3 A4 A5); | |
70 | @EXPORT_OK = qw(B1 B2 B3 B4 B5); | |
71 | %EXPORT_TAGS = (T1=>[qw(A1 A2 B1 B2)], T2=>[qw(A1 A2 B3 B4)], T3=>[qw(X3)]); | |
72 | @EXPORT_FAIL = qw(B4); | |
73 | Exporter::export_ok_tags('T3', 'unknown_tag'); | |
74 | sub export_fail { | |
75 | map { "Test::$_" } @_ # edit symbols just as an example | |
76 | } | |
77 | ||
78 | package main; | |
79 | $Exporter::Verbose = 1; | |
80 | #import Test; | |
81 | #import Test qw(X3); # export ok via export_ok_tags() | |
82 | #import Test qw(:T1 !A2 /5/ !/3/ B5); | |
83 | import Test qw(:T2 !B4); | |
84 | import Test qw(:T2); # should fail | |
85 | 1; | |
86 | ||
87 | =head1 NAME | |
88 | ||
89 | Exporter - Implements default import method for modules | |
90 | ||
91 | =head1 SYNOPSIS | |
92 | ||
93 | In module ModuleName.pm: | |
94 | ||
95 | package ModuleName; | |
96 | require Exporter; | |
97 | @ISA = qw(Exporter); | |
98 | ||
99 | @EXPORT = qw(...); # symbols to export by default | |
100 | @EXPORT_OK = qw(...); # symbols to export on request | |
101 | %EXPORT_TAGS = tag => [...]; # define names for sets of symbols | |
102 | ||
103 | In other files which wish to use ModuleName: | |
104 | ||
105 | use ModuleName; # import default symbols into my package | |
106 | ||
107 | use ModuleName qw(...); # import listed symbols into my package | |
108 | ||
109 | use ModuleName (); # do not import any symbols | |
110 | ||
111 | =head1 DESCRIPTION | |
112 | ||
113 | The Exporter module implements a default C<import> method which | |
68dc0745 | 114 | many modules choose to inherit rather than implement their own. |
2b5b2650 | 115 | |
116 | Perl automatically calls the C<import> method when processing a | |
117 | C<use> statement for a module. Modules and C<use> are documented | |
118 | in L<perlfunc> and L<perlmod>. Understanding the concept of | |
119 | modules and how the C<use> statement operates is important to | |
120 | understanding the Exporter. | |
121 | ||
4fddf32b GS |
122 | =head2 How to Export |
123 | ||
124 | The arrays C<@EXPORT> and C<@EXPORT_OK> in a module hold lists of | |
125 | symbols that are going to be exported into the users name space by | |
126 | default, or which they can request to be exported, respectively. The | |
127 | symbols can represent functions, scalars, arrays, hashes, or typeglobs. | |
128 | The symbols must be given by full name with the exception that the | |
129 | ampersand in front of a function is optional, e.g. | |
130 | ||
131 | @EXPORT = qw(afunc $scalar @array); # afunc is a function | |
132 | @EXPORT_OK = qw(&bfunc %hash *typeglob); # explicit prefix on &bfunc | |
133 | ||
2b5b2650 | 134 | =head2 Selecting What To Export |
135 | ||
136 | Do B<not> export method names! | |
137 | ||
138 | Do B<not> export anything else by default without a good reason! | |
139 | ||
140 | Exports pollute the namespace of the module user. If you must export | |
141 | try to use @EXPORT_OK in preference to @EXPORT and avoid short or | |
142 | common symbol names to reduce the risk of name clashes. | |
143 | ||
144 | Generally anything not exported is still accessible from outside the | |
1fef88e7 | 145 | module using the ModuleName::item_name (or $blessed_ref-E<gt>method) |
2b5b2650 | 146 | syntax. By convention you can use a leading underscore on names to |
147 | informally indicate that they are 'internal' and not for public use. | |
148 | ||
149 | (It is actually possible to get private functions by saying: | |
150 | ||
151 | my $subref = sub { ... }; | |
152 | &$subref; | |
153 | ||
154 | But there's no way to call that directly as a method, since a method | |
155 | must have a name in the symbol table.) | |
156 | ||
157 | As a general rule, if the module is trying to be object oriented | |
158 | then export nothing. If it's just a collection of functions then | |
159 | @EXPORT_OK anything but use @EXPORT with caution. | |
160 | ||
161 | Other module design guidelines can be found in L<perlmod>. | |
162 | ||
163 | =head2 Specialised Import Lists | |
164 | ||
165 | If the first entry in an import list begins with !, : or / then the | |
166 | list is treated as a series of specifications which either add to or | |
167 | delete from the list of names to import. They are processed left to | |
168 | right. Specifications are in the form: | |
169 | ||
170 | [!]name This name only | |
171 | [!]:DEFAULT All names in @EXPORT | |
172 | [!]:tag All names in $EXPORT_TAGS{tag} anonymous list | |
173 | [!]/pattern/ All names in @EXPORT and @EXPORT_OK which match | |
174 | ||
175 | A leading ! indicates that matching names should be deleted from the | |
176 | list of names to import. If the first specification is a deletion it | |
177 | is treated as though preceded by :DEFAULT. If you just want to import | |
178 | extra names in addition to the default set you will still need to | |
179 | include :DEFAULT explicitly. | |
180 | ||
181 | e.g., Module.pm defines: | |
182 | ||
183 | @EXPORT = qw(A1 A2 A3 A4 A5); | |
184 | @EXPORT_OK = qw(B1 B2 B3 B4 B5); | |
185 | %EXPORT_TAGS = (T1 => [qw(A1 A2 B1 B2)], T2 => [qw(A1 A2 B3 B4)]); | |
186 | ||
187 | Note that you cannot use tags in @EXPORT or @EXPORT_OK. | |
188 | Names in EXPORT_TAGS must also appear in @EXPORT or @EXPORT_OK. | |
189 | ||
190 | An application using Module can say something like: | |
191 | ||
192 | use Module qw(:DEFAULT :T2 !B3 A3); | |
193 | ||
194 | Other examples include: | |
195 | ||
196 | use Socket qw(!/^[AP]F_/ !SOMAXCONN !SOL_SOCKET); | |
197 | use POSIX qw(:errno_h :termios_h !TCSADRAIN !/^EXIT/); | |
198 | ||
199 | Remember that most patterns (using //) will need to be anchored | |
200 | with a leading ^, e.g., C</^EXIT/> rather than C</EXIT/>. | |
201 | ||
202 | You can say C<BEGIN { $Exporter::Verbose=1 }> to see how the | |
203 | specifications are being processed and what is actually being imported | |
204 | into modules. | |
205 | ||
84902520 TB |
206 | =head2 Exporting without using Export's import method |
207 | ||
208 | Exporter has a special method, 'export_to_level' which is used in situations | |
209 | where you can't directly call Export's import method. The export_to_level | |
210 | method looks like: | |
211 | ||
ba5725f8 | 212 | MyPackage->export_to_level($where_to_export, $package, @what_to_export); |
84902520 TB |
213 | |
214 | where $where_to_export is an integer telling how far up the calling stack | |
215 | to export your symbols, and @what_to_export is an array telling what | |
ba5725f8 GS |
216 | symbols *to* export (usually this is @_). The $package argument is |
217 | currently unused. | |
84902520 TB |
218 | |
219 | For example, suppose that you have a module, A, which already has an | |
220 | import function: | |
221 | ||
222 | package A; | |
223 | ||
224 | @ISA = qw(Exporter); | |
225 | @EXPORT_OK = qw ($b); | |
226 | ||
227 | sub import | |
228 | { | |
229 | $A::b = 1; # not a very useful import method | |
230 | } | |
231 | ||
232 | and you want to Export symbol $A::b back to the module that called | |
233 | package A. Since Exporter relies on the import method to work, via | |
234 | inheritance, as it stands Exporter::import() will never get called. | |
235 | Instead, say the following: | |
236 | ||
237 | package A; | |
238 | @ISA = qw(Exporter); | |
239 | @EXPORT_OK = qw ($b); | |
240 | ||
241 | sub import | |
242 | { | |
243 | $A::b = 1; | |
244 | A->export_to_level(1, @_); | |
245 | } | |
246 | ||
247 | This will export the symbols one level 'above' the current package - ie: to | |
248 | the program or module that used package A. | |
249 | ||
250 | Note: Be careful not to modify '@_' at all before you call export_to_level | |
251 | - or people using your package will get very unexplained results! | |
252 | ||
253 | ||
2b5b2650 | 254 | =head2 Module Version Checking |
255 | ||
256 | The Exporter module will convert an attempt to import a number from a | |
1fef88e7 | 257 | module into a call to $module_name-E<gt>require_version($value). This can |
2b5b2650 | 258 | be used to validate that the version of the module being used is |
259 | greater than or equal to the required version. | |
260 | ||
261 | The Exporter module supplies a default require_version method which | |
262 | checks the value of $VERSION in the exporting module. | |
263 | ||
264 | Since the default require_version method treats the $VERSION number as | |
d5e40bcc | 265 | a simple numeric value it will regard version 1.10 as lower than |
266 | 1.9. For this reason it is strongly recommended that you use numbers | |
267 | with at least two decimal places, e.g., 1.09. | |
2b5b2650 | 268 | |
269 | =head2 Managing Unknown Symbols | |
270 | ||
271 | In some situations you may want to prevent certain symbols from being | |
272 | exported. Typically this applies to extensions which have functions | |
273 | or constants that may not exist on some systems. | |
274 | ||
275 | The names of any symbols that cannot be exported should be listed | |
276 | in the C<@EXPORT_FAIL> array. | |
277 | ||
7a2e2cd6 | 278 | If a module attempts to import any of these symbols the Exporter |
2b5b2650 | 279 | will give the module an opportunity to handle the situation before |
280 | generating an error. The Exporter will call an export_fail method | |
281 | with a list of the failed symbols: | |
282 | ||
283 | @failed_symbols = $module_name->export_fail(@failed_symbols); | |
284 | ||
285 | If the export_fail method returns an empty list then no error is | |
286 | recorded and all the requested symbols are exported. If the returned | |
287 | list is not empty then an error is generated for each symbol and the | |
288 | export fails. The Exporter provides a default export_fail method which | |
289 | simply returns the list unchanged. | |
290 | ||
291 | Uses for the export_fail method include giving better error messages | |
292 | for some symbols and performing lazy architectural checks (put more | |
293 | symbols into @EXPORT_FAIL by default and then take them out if someone | |
294 | actually tries to use them and an expensive check shows that they are | |
295 | usable on that platform). | |
296 | ||
297 | =head2 Tag Handling Utility Functions | |
298 | ||
299 | Since the symbols listed within %EXPORT_TAGS must also appear in either | |
300 | @EXPORT or @EXPORT_OK, two utility functions are provided which allow | |
301 | you to easily add tagged sets of symbols to @EXPORT or @EXPORT_OK: | |
302 | ||
303 | %EXPORT_TAGS = (foo => [qw(aa bb cc)], bar => [qw(aa cc dd)]); | |
304 | ||
305 | Exporter::export_tags('foo'); # add aa, bb and cc to @EXPORT | |
306 | Exporter::export_ok_tags('bar'); # add aa, cc and dd to @EXPORT_OK | |
307 | ||
308 | Any names which are not tags are added to @EXPORT or @EXPORT_OK | |
d5e40bcc | 309 | unchanged but will trigger a warning (with C<-w>) to avoid misspelt tags |
2b5b2650 | 310 | names being silently added to @EXPORT or @EXPORT_OK. Future versions |
311 | may make this a fatal error. | |
312 | ||
313 | =cut |