3 version - Perl extension for Version Objects
7 # Parsing version strings (decimal or dotted-decimal)
9 use version 0.77; # get latest bug-fixes and API
10 $ver = version->parse($string)
12 # Declaring a dotted-decimal $VERSION (keep on one line!)
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
18 # Declaring an old-style decimal $VERSION (use quotes!)
20 use version 0.77; our $VERSION = version->parse("1.0203"); # formal
21 use version 0.77; our $VERSION = version->parse("1.02_03"); # alpha
23 # Comparing mixed version styles (decimals, dotted-decimals, objects)
25 if ( version->parse($v1) == version->parse($v2) ) {
29 # Sorting mixed version styles
31 @ordered = sort { version->parse($a) <=> version->parse($b) } @list;
35 Version objects were added to Perl in 5.10. This module implements version
36 objects for older version of Perl and provides the version object API for all
37 versions of Perl. All previous releases before 0.74 are deprecated and should
38 not 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
40 set 0.77 as a minimum in your code, e.g.
42 use version 0.77; # even for Perl v.5.10.0
44 =head1 TYPES OF VERSION OBJECTS
46 There are two different types of version objects, corresponding to the two
47 different styles of versions in use:
51 =item Decimal Versions
53 The classic floating-point number $VERSION. The advantage to this style is
54 that you don't need to do anything special, just type a number (without
55 quotes) into your source file.
57 =item Dotted Decimal Versions
59 The more modern form of version assignment, with 3 (or potentially more)
60 integers seperated by decimal points (e.g. v1.2.3). This is the form that
61 Perl itself has used since 5.6.0 was released. The leading "v" is now
62 strongly recommended for clarity, and will throw a warning in a future
67 See L<VERSION OBJECT DETAILS> for further information.
69 =head1 DECLARING VERSIONS
71 If you have a module that uses a decimal $VERSION (floating point), and you
72 do not intend to ever change that, this module is not for you. There is
73 nothing that version.pm gains you over a simple $VERSION assignment:
77 Since Perl v5.10.0 includes the version.pm comparison logic anyways,
78 you don't need to do anything at all.
80 =head2 How to convert a module from decimal to dotted-decimal
82 If you have used a decimal $VERSION in the past and wish to switch to a
83 dotted-decimal $VERSION, then you need to make a one-time conversion to
86 B<Important Note>: you must ensure that your new $VERSION is numerically
87 greater than your current decimal $VERSION; this is not always obvious. First,
88 convert your old decimal version (e.g. 1.02) to a normalized dotted-decimal
91 $ perl -Mversion -e 'print version->parse("1.02")->normal'
94 Then increment any of the dotted-decimal components (v1.20.1 or v1.21.0).
96 =head2 How to C<declare()> a dotted-decimal version
98 use version 0.77; our $VERSION = version->declare("v1.2.3");
100 The C<declare()> method always creates dotted-decimal version objects. When
101 used in a module, you B<must> put it on the same line as "use version" to
102 ensure that $VERSION is read correctly by PAUSE and installer tools. You
103 should also add 'version' to the 'configure_requires' section of your
104 module metadata file. See instructions in L<ExtUtils::MakeMaker> or
105 L<Module::Build> for details.
107 B<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
109 or unintentional errors on older Perls, follow these guidelines:
115 Always use a dotted-decimal with (at least) three components
119 Always use a leading-v
123 Always quote the version
127 If you really insist on using version.pm with an ordinary decimal version,
128 use C<parse()> instead of declare. See the L<PARSING AND COMPARING VERSIONS>
131 See also L<VERSION OBJECT DETAILS> for more on version number conversion,
132 quoting, calculated version numbers and declaring developer or "alpha" version
135 =head1 PARSING AND COMPARING VERSIONS
137 If you need to compare version numbers, but can't be sure whether they are
138 expressed as numbers, strings, v-strings or version objects, then you can
139 use version.pm to parse them all into objects for comparison.
141 =head2 How to C<parse()> a version
143 The C<parse()> method takes in anything that might be a version and returns
144 a corresponding version object, doing any necessary conversion along the way.
150 Dotted-decimal: bare v-strings (v1.2.3) and strings with more than one
151 decimal point and a leading 'v' ("v1.2.3"); NOTE you can technically use a
152 v-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.
157 Decimal: regular decimal numbers (literal or in a string)
163 $variable version->parse($variable)
164 --------- -------------------------
172 See L<VERSION OBJECT DETAILS> for more on version number conversion.
174 =head2 How to check for a version
176 If you do not want to actually create a full blown version object, but
177 would still like to verify that a given string meets the criteria to
178 be parsed as a version, there are now regular expressions included with
179 the version module and there are two helper functions that can be
186 If you want to limit youself to a much more narrow definition of what
187 a version string constitutes, you can use this function, which limits
188 legal version strings to the following list:
194 For dotted-decimal versions, requires a leading 'v', three sub-versions
195 of no more than three digits. A leading 0 (zero) before the first
196 sub-version (in the above example, '1') is also prohibited.
200 For standard decimal version, requires an integer portion (no leading
201 0), a decimal, and one or more digits to the right of the decimal
213 With the lax criteria, all of the above styles are acceptable for
214 dotted-decimal formats. The leading 'v' is optional if two or more
215 decimals appear. If only a single decimal is included, then the leading
216 'v' is required to trigger the dotted-decimal parsing. A leading zero
217 is permitted, though not recommended except when quoted, because of the
218 risk that Perl will treat the number as octal. A trailing underscore
219 plus one or more digits denotes an alpha or development release
220 (and must be quoted to be parsed properly).
225 For decimal versions, the lax form is nearly identical to the strict
226 form except that the alpha form is allowed and a leading zero is
227 permitted. Just like the lax dotted-decimal version, quoting the
228 values is required for alpha/development forms to be parsed correctly.
232 See L<version::Internal> for details of the regular expressions used,
233 as well as how to use the regular expressions in your own code.
237 =head2 How to compare version objects
239 Version objects overload the C<cmp> and C<< E<lt>=E<gt> >> operators. Perl
240 automatically generates all of the other comparison operators based on those
241 two so all the normal logical comparisons will work.
243 if ( version->parse($v1) == version->parse($v2) ) {
247 If a version object is compared against a non-version object, the non-object
248 term will be converted to a version object using C<parse()>. This may give
251 $v1 = version->parse("v0.95.0");
252 $bool = $v1 < 0.96; # FALSE since 0.96 is v0.960.0
254 Always comparing to a version object will help avoid surprises:
256 $bool = $v1 < version->parse("v0.96.0"); # TRUE
258 =head1 VERSION OBJECT DETAILS
260 =head2 Equivalence between Decimal and Dotted-Decimal Versions
262 When Perl 5.6.0 was released, the decision was made to provide a
263 transformation between the old-style decimal versions and new-style
264 dotted-decimal versions:
269 The floating point number is taken and split first on the single decimal
270 place, then each group of three digits to the right of the decimal makes up
271 the next digit, and so on until the number of significant digits is exhausted,
272 B<plus> enough trailing zeros to reach the next multiple of three.
274 This was the method that version.pm adopted as well. Some examples may be
278 decimal zero-padded dotted-decimal
279 ------- ----------- --------------
283 1.0023 1.002300 v1.2.300
284 1.00203 1.002030 v1.2.30
285 1.002003 1.002003 v1.2.3
289 Because of the nature of the Perl parsing and tokenizing routines,
290 certain initialization values B<must> be quoted in order to correctly
291 parse as the intended version, especially when using the L<declare> or
292 L<qv> methods. While you do not have to quote decimal numbers when
293 creating version objects, it is always safe to quote B<all> initial values
294 when using version.pm methods, as this will ensure that what you type is
297 Additionally, if you quote your initializer, then the quoted value that goes
298 B<in> will be be exactly what comes B<out> when your $VERSION is printed
299 (stringified). If you do not quote your value, Perl's normal numeric handling
300 comes into play and you may not get back what you were expecting.
302 If you use a mathematic formula that resolves to a floating point number,
303 you are dependent on Perl's conversion routines to yield the version you
304 expect. You are pretty safe by dividing by a power of 10, for example,
305 but other operations are not likely to be what you intend. For example:
307 $VERSION = version->new((qw$Revision: 1.4)[1]/10);
308 print $VERSION; # yields 0.14
309 $V2 = version->new(100/9); # Integer overflow in decimal number
310 print $V2; # yields something like 11.111.111.100
312 Perl 5.8.1 and beyond are able to automatically quote v-strings but
313 that is not possible in earlier versions of Perl. In other words:
315 $version = version->new("v2.5.4"); # legal in all versions of Perl
316 $newvers = version->new(v2.5.4); # legal only in Perl >= 5.8.1
318 =head2 What about v-strings?
320 There are two ways to enter v-strings: a bare number with two or more
321 decimal points, or a bare number with one or more decimal points and a
322 leading 'v' character (also bare). For example:
324 $vs1 = 1.2.3; # encoded as \1\2\3
325 $vs2 = v1.2; # encoded as \1\2
327 However, the use of bare v-strings to initialize version objects is
328 B<strongly> discouraged in all circumstances. Also, bare
329 v-strings are not completely supported in any version of Perl prior to
332 If you insist on using bare v-strings with Perl > 5.6.0, be aware of the
333 following limitations:
335 1) For Perl releases 5.6.0 through 5.8.0, the v-string code merely guesses,
336 based on some characteristics of v-strings. You B<must> use a three part
337 version, e.g. 1.2.3 or v1.2.3 in order for this heuristic to be successful.
339 2) For Perl releases 5.8.1 and later, v-strings have changed in the Perl
340 core to be magical, which means that the version.pm code can automatically
341 determine whether the v-string encoding was used.
343 3) In all cases, a version created using v-strings will have a stringified
344 form that has a leading 'v' character, for the simple reason that sometimes
345 it is impossible to tell whether one was present initially.
347 =head2 Alpha versions
349 For module authors using CPAN, the convention has been to note unstable
350 releases with an underscore in the version string. (See L<CPAN>.) version.pm
351 follows this convention and alpha releases will test as being newer than the
352 more recent stable release, and less than the next stable release. For
353 dotted-decimal versions, only the last element may be separated by an
357 use version 0.77; our $VERSION = version->declare("v1.2_3");
360 $v1 = version->parse("v1.2_3");
361 $v1 = version->parse("1.002_003");
363 =head1 OBJECT METHODS
367 True if and only if the version object was created with a underscore, e.g.
369 version->parse('1.002_03')->is_alpha; # TRUE
370 version->declare('1.2.3_4')->is_alpha; # TRUE
374 True only if the version object is a dotted-decimal version, e.g.
376 version->parse('v1.2.0')->is_qv; # TRUE
377 version->declare('v1.2')->is_qv; # TRUE
378 qv('1.2')->is_qv; # TRUE
379 version->parse('1.2')->is_qv; # FALSE
383 Returns a string with a standard 'normalized' dotted-decimal form with a
384 leading-v and at least 3 components.
386 version->declare('v1.2')->normal; # v1.2.0
387 version->parse('1.2')->normal; # v1.200.0
391 Returns a value representing the object in a pure decimal form without
394 version->declare('v1.2')->numify; # 1.002
395 version->parse('1.2')->numify; # 1.2
399 Returns a string that is as close to the original representation as possible.
400 If the original representation was a numeric literal, it will be returned the
401 way perl would normally represent it in a string. This method is used whenever
402 a version object is interpolated into a string.
404 version->declare('v1.2')->stringify; # v1.2
405 version->parse('1.200')->stringify; # 1.200
406 version->parse(1.02_30)->stringify; # 1.023
408 =head1 EXPORTED FUNCTIONS
412 This function is no longer recommended for use, but is maintained for
413 compatibility with existing code. If you do not want to have it exported
414 to your namespace, use this form:
420 John Peacock E<lt>jpeacock@cpan.orgE<gt>
424 L<version::Internal>.