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Document usage of version regexps
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1=head1 NAME
2
3version - Perl extension for Version Objects
4
5=head1 SYNOPSIS
6
692a467c 7 # Parsing version strings (decimal or dotted-decimal)
cb5772bb 8
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9 use version 0.77; # get latest bug-fixes and API
10 $ver = version->parse($string)
cb5772bb 11
692a467c 12 # Declaring a dotted-decimal $VERSION (keep on one line!)
cb5772bb 13
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14 use version 0.77; our $VERSION = version->declare("v1.2.3"); # formal
15 use version 0.77; our $VERSION = qv("v1.2.3"); # shorthand
16 use version 0.77; our $VERSION = qv("v1.2_3"); # alpha
317f7c8a 17
692a467c 18 # Declaring an old-style decimal $VERSION (use quotes!)
317f7c8a 19
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20 use version 0.77; our $VERSION = version->parse("1.0203"); # formal
21 use version 0.77; our $VERSION = version->parse("1.02_03"); # alpha
317f7c8a 22
692a467c 23 # Comparing mixed version styles (decimals, dotted-decimals, objects)
317f7c8a 24
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25 if ( version->parse($v1) == version->parse($v2) ) {
26 # do stuff
27 }
317f7c8a 28
692a467c 29 # Sorting mixed version styles
317f7c8a 30
692a467c 31 @ordered = sort { version->parse($a) <=> version->parse($b) } @list;
317f7c8a 32
692a467c 33=head1 DESCRIPTION
317f7c8a 34
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35Version objects were added to Perl in 5.10. This module implements version
36objects for older version of Perl and provides the version object API for all
37versions of Perl. All previous releases before 0.74 are deprecated and should
38not be used due to incompatible API changes. Version 0.77 introduces the new
39'parse' and 'declare' methods to standardize usage. You are strongly urged to
61a0cb1c 40set 0.77 as a minimum in your code, e.g.
317f7c8a 41
692a467c 42 use version 0.77; # even for Perl v.5.10.0
cb5772bb 43
692a467c 44=head1 TYPES OF VERSION OBJECTS
cb5772bb 45
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46There are two different types of version objects, corresponding to the two
47different styles of versions in use:
cb5772bb 48
692a467c 49=over 2
cb5772bb 50
692a467c 51=item Decimal Versions
cb5772bb 52
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53The classic floating-point number $VERSION. The advantage to this style is
54that you don't need to do anything special, just type a number (without
55quotes) into your source file.
cb5772bb 56
692a467c 57=item Dotted Decimal Versions
cb5772bb 58
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59The more modern form of version assignment, with 3 (or potentially more)
60integers seperated by decimal points (e.g. v1.2.3). This is the form that
61a0cb1c 61Perl itself has used since 5.6.0 was released. The leading "v" is now
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62strongly recommended for clarity, and will throw a warning in a future
63release if omitted.
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64
65=back
66
692a467c 67See L<VERSION OBJECT DETAILS> for further information.
cb5772bb 68
692a467c 69=head1 DECLARING VERSIONS
43eaf59d 70
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71If you have a module that uses a decimal $VERSION (floating point), and you
72do not intend to ever change that, this module is not for you. There is
73nothing that version.pm gains you over a simple $VERSION assignment:
cb5772bb 74
692a467c 75 our $VERSION = 1.02;
cb5772bb 76
61a0cb1c 77Since Perl v5.10.0 includes the version.pm comparison logic anyways,
692a467c 78you don't need to do anything at all.
cb5772bb 79
692a467c 80=head2 How to convert a module from decimal to dotted-decimal
cb5772bb 81
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82If you have used a decimal $VERSION in the past and wish to switch to a
83dotted-decimal $VERSION, then you need to make a one-time conversion to
61a0cb1c 84the new format.
cb5772bb 85
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86B<Important Note>: you must ensure that your new $VERSION is numerically
87greater than your current decimal $VERSION; this is not always obvious. First,
88convert your old decimal version (e.g. 1.02) to a normalized dotted-decimal
89form:
cb5772bb 90
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91 $ perl -Mversion -e 'print version->parse("1.02")->normal'
92 v1.20.0
cb5772bb 93
692a467c 94Then increment any of the dotted-decimal components (v1.20.1 or v1.21.0).
cb5772bb 95
692a467c 96=head2 How to C<declare()> a dotted-decimal version
cb5772bb 97
692a467c 98 use version 0.77; our $VERSION = version->declare("v1.2.3");
cb5772bb 99
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100The C<declare()> method always creates dotted-decimal version objects. When
101used in a module, you B<must> put it on the same line as "use version" to
102ensure that $VERSION is read correctly by PAUSE and installer tools. You
103should also add 'version' to the 'configure_requires' section of your
104module metadata file. See instructions in L<ExtUtils::MakeMaker> or
105L<Module::Build> for details.
cb5772bb 106
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107B<Important Note>: Even if you pass in what looks like a decimal number
108("1.2"), a dotted-decimal will be created ("v1.200.0"). To avoid confusion
109or unintentional errors on older Perls, follow these guidelines:
cb5772bb 110
692a467c 111=over 2
cb5772bb 112
692a467c 113=item *
cb5772bb 114
692a467c 115Always use a dotted-decimal with (at least) three components
92dcf8ce 116
692a467c 117=item *
92dcf8ce 118
692a467c 119Always use a leading-v
92dcf8ce 120
692a467c 121=item *
92dcf8ce 122
692a467c 123Always quote the version
92dcf8ce 124
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125=back
126
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127If you really insist on using version.pm with an ordinary decimal version,
128use C<parse()> instead of declare. See the L<PARSING AND COMPARING VERSIONS>
129for details.
cb5772bb 130
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131See also L<VERSION OBJECT DETAILS> for more on version number conversion,
132quoting, calculated version numbers and declaring developer or "alpha" version
133numbers.
cb5772bb 134
692a467c 135=head1 PARSING AND COMPARING VERSIONS
cb5772bb 136
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137If you need to compare version numbers, but can't be sure whether they are
138expressed as numbers, strings, v-strings or version objects, then you can
139use version.pm to parse them all into objects for comparison.
cb5772bb 140
692a467c 141=head2 How to C<parse()> a version
cb5772bb 142
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143The C<parse()> method takes in anything that might be a version and returns
144a corresponding version object, doing any necessary conversion along the way.
cb5772bb 145
692a467c 146=over 2
cb5772bb 147
692a467c 148=item *
cb5772bb 149
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150Dotted-decimal: bare v-strings (v1.2.3) and strings with more than one
151decimal point and a leading 'v' ("v1.2.3"); NOTE you can technically use a
152v-string or strings with a leading-v and only one decimal point (v1.2 or
153"v1.2"), but you will confuse both yourself and others.
cb5772bb 154
692a467c 155=item *
cb5772bb 156
692a467c 157Decimal: regular decimal numbers (literal or in a string)
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158
159=back
160
692a467c 161Some examples:
cb5772bb 162
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163 $variable version->parse($variable)
164 --------- -------------------------
165 1.23 v1.230.0
166 "1.23" v1.230.0
167 v1.23 v1.23.0
168 "v1.23" v1.23.0
169 "1.2.3" v1.2.3
170 "v1.2.3" v1.2.3
cb5772bb 171
692a467c 172See L<VERSION OBJECT DETAILS> for more on version number conversion.
cb5772bb 173
42bd538f 174=head2 How to check for a legal version string
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175
176If you do not want to actually create a full blown version object, but
177would still like to verify that a given string meets the criteria to
42bd538f 178be parsed as a version, there are two helper functions that can be
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179employed directly:
180
42bd538f 181=over 4
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182
183=item C<is_lax()>
184
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185The lax criteria corresponds to what is currently allowed by the
186version parser. All of the following formats are acceptable
187for dotted-decimal formats strings:
61a0cb1c 188
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189 v1.2
190 1.2345.6
191 v1.23_4
192 1.2345
193 1.2345_01
61a0cb1c 194
42bd538f 195=item C<is_strict()>
61a0cb1c 196
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197If you want to limit youself to a much more narrow definition of what
198a version string constitutes, C<is_strict()> is limited to version
199strings like the following list:
61a0cb1c 200
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201 v1.234.5
202 2.3456
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203
204=back
205
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206See L<version::Internals> for details of the regular expressions
207that define the legal version string forms, as well as how to use
208those regular expressions in your own code.
61a0cb1c 209
692a467c 210=head2 How to compare version objects
cb5772bb 211
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212Version objects overload the C<cmp> and C<< E<lt>=E<gt> >> operators. Perl
213automatically generates all of the other comparison operators based on those
214two so all the normal logical comparisons will work.
cb5772bb 215
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216 if ( version->parse($v1) == version->parse($v2) ) {
217 # do stuff
218 }
219bf418 219
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220If a version object is compared against a non-version object, the non-object
221term will be converted to a version object using C<parse()>. This may give
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222surprising results:
223
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224 $v1 = version->parse("v0.95.0");
225 $bool = $v1 < 0.96; # FALSE since 0.96 is v0.960.0
219bf418 226
692a467c 227Always comparing to a version object will help avoid surprises:
cb5772bb 228
692a467c 229 $bool = $v1 < version->parse("v0.96.0"); # TRUE
cb5772bb 230
692a467c 231=head1 VERSION OBJECT DETAILS
cb5772bb 232
692a467c 233=head2 Equivalence between Decimal and Dotted-Decimal Versions
cb5772bb 234
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235When Perl 5.6.0 was released, the decision was made to provide a
236transformation between the old-style decimal versions and new-style
237dotted-decimal versions:
cb5772bb 238
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239 5.6.0 == 5.006000
240 5.005_04 == 5.5.40
cb5772bb 241
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242The floating point number is taken and split first on the single decimal
243place, then each group of three digits to the right of the decimal makes up
244the next digit, and so on until the number of significant digits is exhausted,
245B<plus> enough trailing zeros to reach the next multiple of three.
cb5772bb 246
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247This was the method that version.pm adopted as well. Some examples may be
248helpful:
cb5772bb 249
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250 equivalent
251 decimal zero-padded dotted-decimal
252 ------- ----------- --------------
253 1.2 1.200 v1.200.0
254 1.02 1.020 v1.20.0
255 1.002 1.002 v1.2.0
256 1.0023 1.002300 v1.2.300
257 1.00203 1.002030 v1.2.30
258 1.002003 1.002003 v1.2.3
cb5772bb 259
692a467c 260=head2 Quoting rules
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261
262Because of the nature of the Perl parsing and tokenizing routines,
263certain initialization values B<must> be quoted in order to correctly
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264parse as the intended version, especially when using the L<declare> or
265L<qv> methods. While you do not have to quote decimal numbers when
266creating version objects, it is always safe to quote B<all> initial values
267when using version.pm methods, as this will ensure that what you type is
268what is used.
269
270Additionally, if you quote your initializer, then the quoted value that goes
271B<in> will be be exactly what comes B<out> when your $VERSION is printed
272(stringified). If you do not quote your value, Perl's normal numeric handling
273comes into play and you may not get back what you were expecting.
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274
275If you use a mathematic formula that resolves to a floating point number,
276you are dependent on Perl's conversion routines to yield the version you
277expect. You are pretty safe by dividing by a power of 10, for example,
278but other operations are not likely to be what you intend. For example:
279
280 $VERSION = version->new((qw$Revision: 1.4)[1]/10);
281 print $VERSION; # yields 0.14
282 $V2 = version->new(100/9); # Integer overflow in decimal number
283 print $V2; # yields something like 11.111.111.100
284
692a467c 285Perl 5.8.1 and beyond are able to automatically quote v-strings but
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286that is not possible in earlier versions of Perl. In other words:
287
288 $version = version->new("v2.5.4"); # legal in all versions of Perl
289 $newvers = version->new(v2.5.4); # legal only in Perl >= 5.8.1
290
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291=head2 What about v-strings?
292
43eaf59d 293There are two ways to enter v-strings: a bare number with two or more
61a0cb1c 294decimal points, or a bare number with one or more decimal points and a
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295leading 'v' character (also bare). For example:
296
297 $vs1 = 1.2.3; # encoded as \1\2\3
61a0cb1c 298 $vs2 = v1.2; # encoded as \1\2
43eaf59d 299
f34c6aaf 300However, the use of bare v-strings to initialize version objects is
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301B<strongly> discouraged in all circumstances. Also, bare
302v-strings are not completely supported in any version of Perl prior to
3035.8.1.
f34c6aaf 304
61a0cb1c 305If you insist on using bare v-strings with Perl > 5.6.0, be aware of the
f34c6aaf 306following limitations:
43eaf59d 307
61a0cb1c 3081) For Perl releases 5.6.0 through 5.8.0, the v-string code merely guesses,
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309based on some characteristics of v-strings. You B<must> use a three part
310version, e.g. 1.2.3 or v1.2.3 in order for this heuristic to be successful.
311
3122) For Perl releases 5.8.1 and later, v-strings have changed in the Perl
313core to be magical, which means that the version.pm code can automatically
314determine whether the v-string encoding was used.
cb5772bb 315
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3163) In all cases, a version created using v-strings will have a stringified
317form that has a leading 'v' character, for the simple reason that sometimes
318it is impossible to tell whether one was present initially.
319
692a467c 320=head2 Alpha versions
cb5772bb 321
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322For module authors using CPAN, the convention has been to note unstable
323releases with an underscore in the version string. (See L<CPAN>.) version.pm
324follows this convention and alpha releases will test as being newer than the
325more recent stable release, and less than the next stable release. For
326dotted-decimal versions, only the last element may be separated by an
327underscore:
cb5772bb 328
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329 # Declaring
330 use version 0.77; our $VERSION = version->declare("v1.2_3");
cb5772bb 331
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332 # Parsing
333 $v1 = version->parse("v1.2_3");
334 $v1 = version->parse("1.002_003");
cb5772bb 335
692a467c 336=head1 OBJECT METHODS
cb5772bb 337
692a467c 338=head2 is_alpha()
cb5772bb 339
692a467c 340True if and only if the version object was created with a underscore, e.g.
cb5772bb 341
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342 version->parse('1.002_03')->is_alpha; # TRUE
343 version->declare('1.2.3_4')->is_alpha; # TRUE
cb5772bb 344
692a467c 345=head2 is_qv()
cb5772bb 346
692a467c 347True only if the version object is a dotted-decimal version, e.g.
cb5772bb 348
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349 version->parse('v1.2.0')->is_qv; # TRUE
350 version->declare('v1.2')->is_qv; # TRUE
351 qv('1.2')->is_qv; # TRUE
352 version->parse('1.2')->is_qv; # FALSE
cb5772bb 353
692a467c 354=head2 normal()
cb5772bb 355
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356Returns a string with a standard 'normalized' dotted-decimal form with a
357leading-v and at least 3 components.
cb5772bb 358
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359 version->declare('v1.2')->normal; # v1.2.0
360 version->parse('1.2')->normal; # v1.200.0
8cb289bd 361
692a467c 362=head2 numify()
8cb289bd 363
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364Returns a value representing the object in a pure decimal form without
365trailing zeroes.
cb5772bb 366
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367 version->declare('v1.2')->numify; # 1.002
368 version->parse('1.2')->numify; # 1.2
cb5772bb 369
692a467c 370=head2 stringify()
cb5772bb 371
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372Returns a string that is as close to the original representation as possible.
373If the original representation was a numeric literal, it will be returned the
374way perl would normally represent it in a string. This method is used whenever
375a version object is interpolated into a string.
cb5772bb 376
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377 version->declare('v1.2')->stringify; # v1.2
378 version->parse('1.200')->stringify; # 1.200
379 version->parse(1.02_30)->stringify; # 1.023
cb5772bb 380
692a467c 381=head1 EXPORTED FUNCTIONS
cb5772bb 382
692a467c 383=head2 qv()
cb5772bb 384
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385This function is no longer recommended for use, but is maintained for
386compatibility with existing code. If you do not want to have it exported
387to your namespace, use this form:
cb5772bb 388
692a467c 389 use version 0.77 ();
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390
391=head1 AUTHOR
392
393John Peacock E<lt>jpeacock@cpan.orgE<gt>
394
395=head1 SEE ALSO
396
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397L<version::Internal>.
398
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399L<perl>.
400
401=cut