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.\" ========================================================================
.\"
.IX Title "version 3perl"
.TH version 3perl 2024-03-06 "perl v5.38.2" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
version \- Perl extension for Version Objects
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&  # Parsing version strings (decimal or dotted\-decimal)
\&
\&  use version 0.77; # get latest bug\-fixes and API
\&  $ver = version\->parse($string)
\&
\&  # Declaring a dotted\-decimal $VERSION (keep on one line!)
\&
\&  use version; our $VERSION = version\->declare("v1.2.3"); # formal
\&  use version; our $VERSION = qv("v1.2.3");               # deprecated
\&  use version; our $VERSION = qv("v1.2_3");               # deprecated
\&
\&  # Declaring an old\-style decimal $VERSION (use quotes!)
\&
\&  our $VERSION = "1.0203";                                # recommended
\&  use version; our $VERSION = version\->parse("1.0203");   # formal
\&  use version; our $VERSION = version\->parse("1.02_03");  # alpha
\&
\&  # Comparing mixed version styles (decimals, dotted\-decimals, objects)
\&
\&  if ( version\->parse($v1) == version\->parse($v2) ) {
\&    # do stuff
\&  }
\&
\&  # Sorting mixed version styles
\&
\&  @ordered = sort { version\->parse($a) <=> version\->parse($b) } @list;
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Version objects were added to Perl in 5.10.  This module implements version
objects for older version of Perl and provides the version object API for all
versions of Perl.  All previous releases before 0.74 are deprecated and should
not be used due to incompatible API changes.  Version 0.77 introduces the new
\&'parse' and 'declare' methods to standardize usage.  You are strongly urged to
set 0.77 as a minimum in your code, e.g.
.PP
.Vb 1
\&  use version 0.77; # even for Perl v.5.10.0
.Ve
.SH "TYPES OF VERSION OBJECTS"
.IX Header "TYPES OF VERSION OBJECTS"
There are two different types of version objects, corresponding to the two
different styles of versions in use:
.IP "Decimal Versions" 2
.IX Item "Decimal Versions"
The classic floating-point number \f(CW$VERSION\fR.  The advantage to this style is
that you don't need to do anything special, just type a number into your
source file.  Quoting is recommended, as it ensures that trailing zeroes
("1.50") are preserved in any warnings or other output.
.IP "Dotted Decimal Versions" 2
.IX Item "Dotted Decimal Versions"
The more modern form of version assignment, with 3 (or potentially more)
integers separated by decimal points (e.g. v1.2.3).  This is the form that
Perl itself has used since 5.6.0 was released.  The leading 'v' is now
strongly recommended for clarity, and will throw a warning in a future
release if omitted.  A leading 'v' character is required to pass the
"\fBis_strict()\fR" test.
.SH "DECLARING VERSIONS"
.IX Header "DECLARING VERSIONS"
If you have a module that uses a decimal \f(CW$VERSION\fR (floating point), and you
do not intend to ever change that, this module is not for you.  There is
nothing that version.pm gains you over a simple \f(CW$VERSION\fR assignment:
.PP
.Vb 1
\&  our $VERSION = "1.02";
.Ve
.PP
Since Perl v5.10.0 includes the version.pm comparison logic anyways,
you don't need to do anything at all.
.SS "How to convert a module from decimal to dotted-decimal"
.IX Subsection "How to convert a module from decimal to dotted-decimal"
If you have used a decimal \f(CW$VERSION\fR in the past and wish to switch to a
dotted-decimal \f(CW$VERSION\fR, then you need to make a one-time conversion to
the new format.
.PP
\&\fBImportant Note\fR: you must ensure that your new \f(CW$VERSION\fR is numerically
greater than your current decimal \f(CW$VERSION\fR; this is not always obvious. First,
convert your old decimal version (e.g. 1.02) to a normalized dotted-decimal
form:
.PP
.Vb 2
\&  $ perl \-Mversion \-e \*(Aqprint version\->parse("1.02")\->normal\*(Aq
\&  v1.20.0
.Ve
.PP
Then increment any of the dotted-decimal components (v1.20.1 or v1.21.0).
.ie n .SS "How to declare() a dotted-decimal version"
.el .SS "How to \f(CWdeclare()\fP a dotted-decimal version"
.IX Subsection "How to declare() a dotted-decimal version"
.Vb 1
\&  use version; our $VERSION = version\->declare("v1.2.3");
.Ve
.PP
The \f(CWdeclare()\fR method always creates dotted-decimal version objects.  When
used in a module, you \fBmust\fR put it on the same line as "use version" to
ensure that \f(CW$VERSION\fR is read correctly by PAUSE and installer tools.  You
should also add 'version' to the 'configure_requires' section of your
module metadata file.  See instructions in ExtUtils::MakeMaker or
Module::Build for details.
.PP
\&\fBImportant Note\fR: Even if you pass in what looks like a decimal number
("1.2"), a dotted-decimal will be created ("v1.200.0"). To avoid confusion
or unintentional errors on older Perls, follow these guidelines:
.IP \(bu 2
Always use a dotted-decimal with (at least) three components
.IP \(bu 2
Always use a leading-v
.IP \(bu 2
Always quote the version
.PP
If you really insist on using version.pm with an ordinary decimal version,
use \f(CWparse()\fR instead of declare.  See the "PARSING AND COMPARING VERSIONS"
for details.
.PP
See also version::Internals for more on version number conversion,
quoting, calculated version numbers and declaring developer or "alpha" version
numbers.
.SH "PARSING AND COMPARING VERSIONS"
.IX Header "PARSING AND COMPARING VERSIONS"
If you need to compare version numbers, but can't be sure whether they are
expressed as numbers, strings, v\-strings or version objects,  then you should
use version.pm to parse them all into objects for comparison.
.ie n .SS "How to parse() a version"
.el .SS "How to \f(CWparse()\fP a version"
.IX Subsection "How to parse() a version"
The \f(CWparse()\fR method takes in anything that might be a version and returns
a corresponding version object, doing any necessary conversion along the way.
.IP \(bu 2
Dotted-decimal: bare v\-strings (v1.2.3) and strings with more than one
decimal point and a leading 'v' ("v1.2.3"); NOTE you can technically use a
v\-string or strings with a leading-v and only one decimal point (v1.2 or
"v1.2"), but you will confuse both yourself and others.
.IP \(bu 2
Decimal: regular decimal numbers (literal or in a string)
.PP
Some examples:
.PP
.Vb 8
\&  $variable   version\->parse($variable)
\&  \-\-\-\-\-\-\-\-\-   \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&  1.23        v1.230.0
\&  "1.23"      v1.230.0
\&  v1.23       v1.23.0
\&  "v1.23"     v1.23.0
\&  "1.2.3"     v1.2.3
\&  "v1.2.3"    v1.2.3
.Ve
.PP
See version::Internals for more on version number conversion.
.SS "How to check for a legal version string"
.IX Subsection "How to check for a legal version string"
If you do not want to actually create a full blown version object, but
would still like to verify that a given string meets the criteria to
be parsed as a version, there are two helper functions that can be
employed directly:
.ie n .IP is_lax() 4
.el .IP \f(CWis_lax()\fR 4
.IX Item "is_lax()"
The lax criteria corresponds to what is currently allowed by the
version parser.  All of the following formats are acceptable
for dotted-decimal formats strings:
.Sp
.Vb 5
\&    v1.2
\&    1.2345.6
\&    v1.23_4
\&    1.2345
\&    1.2345_01
.Ve
.ie n .IP is_strict() 4
.el .IP \f(CWis_strict()\fR 4
.IX Item "is_strict()"
If you want to limit yourself to a much more narrow definition of what
a version string constitutes, \f(CWis_strict()\fR is limited to version
strings like the following list:
.Sp
.Vb 2
\&    v1.234.5
\&    2.3456
.Ve
.PP
See version::Internals for details of the regular expressions
that define the legal version string forms, as well as how to use
those regular expressions in your own code if \f(CWis_lax()\fR and
\&\f(CWis_strict()\fR are not sufficient for your needs.
.SS "How to compare version objects"
.IX Subsection "How to compare version objects"
Version objects overload the \f(CW\*(C`cmp\*(C'\fR and \f(CW\*(C`<=>\*(C'\fR operators.  Perl
automatically generates all of the other comparison operators based on those
two so all the normal logical comparisons will work.
.PP
.Vb 3
\&  if ( version\->parse($v1) == version\->parse($v2) ) {
\&    # do stuff
\&  }
.Ve
.PP
If a version object is compared against a non-version object, the non-object
term will be converted to a version object using \f(CWparse()\fR.  This may give
surprising results:
.PP
.Vb 2
\&  $v1 = version\->parse("v0.95.0");
\&  $bool = $v1 < 0.94; # TRUE since 0.94 is v0.940.0
.Ve
.PP
Always comparing to a version object will help avoid surprises:
.PP
.Vb 1
\&  $bool = $v1 < version\->parse("v0.94.0"); # FALSE
.Ve
.PP
Note that "alpha" version objects (where the version string contains
a trailing underscore segment) compare as less than the equivalent
version without an underscore:
.PP
.Vb 1
\&  $bool = version\->parse("1.23_45") < version\->parse("1.2345"); # TRUE
.Ve
.PP
See version::Internals for more details on "alpha" versions.
.SH "OBJECT METHODS"
.IX Header "OBJECT METHODS"
.SS \fBis_alpha()\fP
.IX Subsection "is_alpha()"
True if and only if the version object was created with a underscore, e.g.
.PP
.Vb 2
\&  version\->parse(\*(Aq1.002_03\*(Aq)\->is_alpha;  # TRUE
\&  version\->declare(\*(Aq1.2.3_4\*(Aq)\->is_alpha; # TRUE
.Ve
.SS \fBis_qv()\fP
.IX Subsection "is_qv()"
True only if the version object is a dotted-decimal version, e.g.
.PP
.Vb 4
\&  version\->parse(\*(Aqv1.2.0\*(Aq)\->is_qv;       # TRUE
\&  version\->declare(\*(Aqv1.2\*(Aq)\->is_qv;       # TRUE
\&  qv(\*(Aq1.2\*(Aq)\->is_qv;                      # TRUE
\&  version\->parse(\*(Aq1.2\*(Aq)\->is_qv;          # FALSE
.Ve
.SS \fBnormal()\fP
.IX Subsection "normal()"
Returns a string with a standard 'normalized' dotted-decimal form with a
leading-v and at least 3 components.
.PP
.Vb 2
\& version\->declare(\*(Aqv1.2\*(Aq)\->normal;  # v1.2.0
\& version\->parse(\*(Aq1.2\*(Aq)\->normal;     # v1.200.0
.Ve
.SS \fBnumify()\fP
.IX Subsection "numify()"
Returns a value representing the object in a pure decimal.
.PP
.Vb 2
\& version\->declare(\*(Aqv1.2\*(Aq)\->numify;  # 1.002000
\& version\->parse(\*(Aq1.2\*(Aq)\->numify;     # 1.200
.Ve
.SS \fBstringify()\fP
.IX Subsection "stringify()"
Returns a string that is as close to the original representation as possible.
If the original representation was a numeric literal, it will be returned the
way perl would normally represent it in a string.  This method is used whenever
a version object is interpolated into a string.
.PP
.Vb 3
\& version\->declare(\*(Aqv1.2\*(Aq)\->stringify;    # v1.2
\& version\->parse(\*(Aq1.200\*(Aq)\->stringify;     # 1.2
\& version\->parse(1.02_30)\->stringify;     # 1.023
.Ve
.SH "EXPORTED FUNCTIONS"
.IX Header "EXPORTED FUNCTIONS"
.SS \fBqv()\fP
.IX Subsection "qv()"
This function is no longer recommended for use, but is maintained for
compatibility with existing code.  If you do not want to have it exported
to your namespace, use this form:
.PP
.Vb 1
\&  use version 0.77 ();
.Ve
.SS \fBis_lax()\fP
.IX Subsection "is_lax()"
(Not exported by default)
.PP
This function takes a scalar argument and returns a boolean value indicating
whether the argument meets the "lax" rules for a version number.  Leading and
trailing spaces are not allowed.
.SS \fBis_strict()\fP
.IX Subsection "is_strict()"
(Not exported by default)
.PP
This function takes a scalar argument and returns a boolean value indicating
whether the argument meets the "strict" rules for a version number.  Leading
and trailing spaces are not allowed.
.SH AUTHOR
.IX Header "AUTHOR"
John Peacock <jpeacock@cpan.org>
.SH "SEE ALSO"
.IX Header "SEE ALSO"
version::Internals.
.PP
perl.