1version(3)            User Contributed Perl Documentation           version(3)
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NAME

6       version - Perl extension for Version Objects
7

SYNOPSIS

9         # Parsing version strings (decimal or dotted-decimal)
10
11         use version 0.77; # get latest bug-fixes and API
12         $ver = version->parse($string)
13
14         # Declaring a dotted-decimal $VERSION (keep on one line!)
15
16         use version; our $VERSION = version->declare("v1.2.3"); # formal
17         use version; our $VERSION = qv("v1.2.3");               # deprecated
18         use version; our $VERSION = qv("v1.2_3");               # deprecated
19
20         # Declaring an old-style decimal $VERSION (use quotes!)
21
22         our $VERSION = "1.0203";                                # recommended
23         use version; our $VERSION = version->parse("1.0203");   # formal
24         use version; our $VERSION = version->parse("1.02_03");  # alpha
25
26         # Comparing mixed version styles (decimals, dotted-decimals, objects)
27
28         if ( version->parse($v1) == version->parse($v2) ) {
29           # do stuff
30         }
31
32         # Sorting mixed version styles
33
34         @ordered = sort { version->parse($a) <=> version->parse($b) } @list;
35

DESCRIPTION

37       Version objects were added to Perl in 5.10.  This module implements
38       version objects for older version of Perl and provides the version
39       object API for all versions of Perl.  All previous releases before 0.74
40       are deprecated and should not be used due to incompatible API changes.
41       Version 0.77 introduces the new 'parse' and 'declare' methods to
42       standardize usage.  You are strongly urged to set 0.77 as a minimum in
43       your code, e.g.
44
45         use version 0.77; # even for Perl v.5.10.0
46

TYPES OF VERSION OBJECTS

48       There are two different types of version objects, corresponding to the
49       two different styles of versions in use:
50
51       Decimal Versions
52         The classic floating-point number $VERSION.  The advantage to this
53         style is that you don't need to do anything special, just type a
54         number into your source file.  Quoting is recommended, as it ensures
55         that trailing zeroes ("1.50") are preserved in any warnings or other
56         output.
57
58       Dotted Decimal Versions
59         The more modern form of version assignment, with 3 (or potentially
60         more) integers separated by decimal points (e.g. v1.2.3).  This is
61         the form that Perl itself has used since 5.6.0 was released.  The
62         leading 'v' is now strongly recommended for clarity, and will throw a
63         warning in a future release if omitted.  A leading 'v' character is
64         required to pass the "is_strict()" test.
65

DECLARING VERSIONS

67       If you have a module that uses a decimal $VERSION (floating point), and
68       you do not intend to ever change that, this module is not for you.
69       There is nothing that version.pm gains you over a simple $VERSION
70       assignment:
71
72         our $VERSION = "1.02";
73
74       Since Perl v5.10.0 includes the version.pm comparison logic anyways,
75       you don't need to do anything at all.
76
77   How to convert a module from decimal to dotted-decimal
78       If you have used a decimal $VERSION in the past and wish to switch to a
79       dotted-decimal $VERSION, then you need to make a one-time conversion to
80       the new format.
81
82       Important Note: you must ensure that your new $VERSION is numerically
83       greater than your current decimal $VERSION; this is not always obvious.
84       First, convert your old decimal version (e.g. 1.02) to a normalized
85       dotted-decimal form:
86
87         $ perl -Mversion -e 'print version->parse("1.02")->normal'
88         v1.20.0
89
90       Then increment any of the dotted-decimal components (v1.20.1 or
91       v1.21.0).
92
93   How to "declare()" a dotted-decimal version
94         use version; our $VERSION = version->declare("v1.2.3");
95
96       The "declare()" method always creates dotted-decimal version objects.
97       When used in a module, you must put it on the same line as "use
98       version" to ensure that $VERSION is read correctly by PAUSE and
99       installer tools.  You should also add 'version' to the
100       'configure_requires' section of your module metadata file.  See
101       instructions in ExtUtils::MakeMaker or Module::Build for details.
102
103       Important Note: Even if you pass in what looks like a decimal number
104       ("1.2"), a dotted-decimal will be created ("v1.200.0"). To avoid
105       confusion or unintentional errors on older Perls, follow these
106       guidelines:
107
108       · Always use a dotted-decimal with (at least) three components
109
110       · Always use a leading-v
111
112       · Always quote the version
113
114       If you really insist on using version.pm with an ordinary decimal
115       version, use "parse()" instead of declare.  See the "PARSING AND
116       COMPARING VERSIONS" for details.
117
118       See also version::Internals for more on version number conversion,
119       quoting, calculated version numbers and declaring developer or "alpha"
120       version numbers.
121

PARSING AND COMPARING VERSIONS

123       If you need to compare version numbers, but can't be sure whether they
124       are expressed as numbers, strings, v-strings or version objects,  then
125       you should use version.pm to parse them all into objects for
126       comparison.
127
128   How to "parse()" a version
129       The "parse()" method takes in anything that might be a version and
130       returns a corresponding version object, doing any necessary conversion
131       along the way.
132
133       · Dotted-decimal: bare v-strings (v1.2.3) and strings with more than
134         one decimal point and a leading 'v' ("v1.2.3"); NOTE you can
135         technically use a v-string or strings with a leading-v and only one
136         decimal point (v1.2 or "v1.2"), but you will confuse both yourself
137         and others.
138
139       · Decimal: regular decimal numbers (literal or in a string)
140
141       Some examples:
142
143         $variable   version->parse($variable)
144         ---------   -------------------------
145         1.23        v1.230.0
146         "1.23"      v1.230.0
147         v1.23       v1.23.0
148         "v1.23"     v1.23.0
149         "1.2.3"     v1.2.3
150         "v1.2.3"    v1.2.3
151
152       See version::Internals for more on version number conversion.
153
154   How to check for a legal version string
155       If you do not want to actually create a full blown version object, but
156       would still like to verify that a given string meets the criteria to be
157       parsed as a version, there are two helper functions that can be
158       employed directly:
159
160       "is_lax()"
161           The lax criteria corresponds to what is currently allowed by the
162           version parser.  All of the following formats are acceptable for
163           dotted-decimal formats strings:
164
165               v1.2
166               1.2345.6
167               v1.23_4
168               1.2345
169               1.2345_01
170
171       "is_strict()"
172           If you want to limit yourself to a much more narrow definition of
173           what a version string constitutes, "is_strict()" is limited to
174           version strings like the following list:
175
176               v1.234.5
177               2.3456
178
179       See version::Internals for details of the regular expressions that
180       define the legal version string forms, as well as how to use those
181       regular expressions in your own code if "is_lax()" and "is_strict()"
182       are not sufficient for your needs.
183
184   How to compare version objects
185       Version objects overload the "cmp" and "<=>" operators.  Perl
186       automatically generates all of the other comparison operators based on
187       those two so all the normal logical comparisons will work.
188
189         if ( version->parse($v1) == version->parse($v2) ) {
190           # do stuff
191         }
192
193       If a version object is compared against a non-version object, the non-
194       object term will be converted to a version object using "parse()".
195       This may give surprising results:
196
197         $v1 = version->parse("v0.95.0");
198         $bool = $v1 < 0.96; # FALSE since 0.96 is v0.960.0
199
200       Always comparing to a version object will help avoid surprises:
201
202         $bool = $v1 < version->parse("v0.96.0"); # TRUE
203
204       Note that "alpha" version objects (where the version string contains a
205       trailing underscore segment) compare as less than the equivalent
206       version without an underscore:
207
208         $bool = version->parse("1.23_45") < version->parse("1.2345"); # TRUE
209
210       See version::Internals for more details on "alpha" versions.
211

OBJECT METHODS

213   is_alpha()
214       True if and only if the version object was created with a underscore,
215       e.g.
216
217         version->parse('1.002_03')->is_alpha;  # TRUE
218         version->declare('1.2.3_4')->is_alpha; # TRUE
219
220   is_qv()
221       True only if the version object is a dotted-decimal version, e.g.
222
223         version->parse('v1.2.0')->is_qv;       # TRUE
224         version->declare('v1.2')->is_qv;       # TRUE
225         qv('1.2')->is_qv;                      # TRUE
226         version->parse('1.2')->is_qv;          # FALSE
227
228   normal()
229       Returns a string with a standard 'normalized' dotted-decimal form with
230       a leading-v and at least 3 components.
231
232        version->declare('v1.2')->normal;  # v1.2.0
233        version->parse('1.2')->normal;     # v1.200.0
234
235   numify()
236       Returns a value representing the object in a pure decimal.
237
238        version->declare('v1.2')->numify;  # 1.002000
239        version->parse('1.2')->numify;     # 1.200
240
241   stringify()
242       Returns a string that is as close to the original representation as
243       possible.  If the original representation was a numeric literal, it
244       will be returned the way perl would normally represent it in a string.
245       This method is used whenever a version object is interpolated into a
246       string.
247
248        version->declare('v1.2')->stringify;    # v1.2
249        version->parse('1.200')->stringify;     # 1.2
250        version->parse(1.02_30)->stringify;     # 1.023
251

EXPORTED FUNCTIONS

253   qv()
254       This function is no longer recommended for use, but is maintained for
255       compatibility with existing code.  If you do not want to have it
256       exported to your namespace, use this form:
257
258         use version 0.77 ();
259
260   is_lax()
261       (Not exported by default)
262
263       This function takes a scalar argument and returns a boolean value
264       indicating whether the argument meets the "lax" rules for a version
265       number.  Leading and trailing spaces are not allowed.
266
267   is_strict()
268       (Not exported by default)
269
270       This function takes a scalar argument and returns a boolean value
271       indicating whether the argument meets the "strict" rules for a version
272       number.  Leading and trailing spaces are not allowed.
273

AUTHOR

275       John Peacock <jpeacock@cpan.org>
276

SEE ALSO

278       version::Internals.
279
280       perl.
281
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284perl v5.28.0                      2018-04-12                        version(3)
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