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version(3)	       Perl Programmers	Reference Guide		    version(3)

NAME
       version - Perl extension	for Version Objects

SYNOPSIS
	 # 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;

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.

	 use version 0.77; # even for Perl v.5.10.0

TYPES OF VERSION OBJECTS
       There are two different types of	version	objects, corresponding to the
       two different styles of versions	in use:

       Decimal Versions
	 The classic floating-point number $VERSION.  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.

       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 "is_strict()" test.

DECLARING VERSIONS
       If you have a module that uses a	decimal	$VERSION (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	$VERSION
       assignment:

	 our $VERSION =	"1.02";

       Since Perl v5.10.0 includes the version.pm comparison logic anyways,
       you don't need to do anything at	all.

   How to convert a module from	decimal	to dotted-decimal
       If you have used	a decimal $VERSION in the past and wish	to switch to a
       dotted-decimal $VERSION,	then you need to make a	one-time conversion to
       the new format.

       Important Note: you must	ensure that your new $VERSION is numerically
       greater than your current decimal $VERSION; this	is not always obvious.
       First, convert your old decimal version (e.g. 1.02) to a	normalized
       dotted-decimal form:

	 $ perl	-Mversion -e 'print version->parse("1.02")->normal'
	 v1.20.0

       Then increment any of the dotted-decimal	components (v1.20.1 or
       v1.21.0).

   How to "declare()" a	dotted-decimal version
	 use version; our $VERSION = version->declare("v1.2.3");

       The "declare()" method always creates dotted-decimal version objects.
       When used in a module, you must put it on the same line as "use
       version"	to ensure that $VERSION	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.

       Important Note: 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:

       o Always	use a dotted-decimal with (at least) three components

       o Always	use a leading-v

       o Always	quote the version

       If you really insist on using version.pm	with an	ordinary decimal
       version,	use "parse()" instead of declare.  See the "PARSING AND
       COMPARING VERSIONS" for details.

       See also	version::Internals for more on version number conversion,
       quoting,	calculated version numbers and declaring developer or "alpha"
       version numbers.

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.

   How to "parse()" a version
       The "parse()" method takes in anything that might be a version and
       returns a corresponding version object, doing any necessary conversion
       along the way.

       o 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.

       o Decimal: regular decimal numbers (literal or in a string)

       Some examples:

	 $variable   version->parse($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

       See version::Internals for more on version number conversion.

   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:

       "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:

	       v1.2
	       1.2345.6
	       v1.23_4
	       1.2345
	       1.2345_01

       "is_strict()"
	   If you want to limit	yourself to a much more	narrow definition of
	   what	a version string constitutes, "is_strict()" is limited to
	   version strings like	the following list:

	       v1.234.5
	       2.3456

       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 "is_lax()" and "is_strict()"
       are not sufficient for your needs.

   How to compare version objects
       Version objects overload	the "cmp" and "<=>" operators.	Perl
       automatically generates all of the other	comparison operators based on
       those two so all	the normal logical comparisons will work.

	 if ( version->parse($v1) == version->parse($v2) ) {
	   # do	stuff
	 }

       If a version object is compared against a non-version object, the non-
       object term will	be converted to	a version object using "parse()".
       This may	give surprising	results:

	 $v1 = version->parse("v0.95.0");
	 $bool = $v1 < 0.96; # FALSE since 0.96	is v0.960.0

       Always comparing	to a version object will help avoid surprises:

	 $bool = $v1 < version->parse("v0.96.0"); # TRUE

       Note that "alpha" version objects (where	the version string contains a
       trailing	underscore segment) compare as less than the equivalent
       version without an underscore:

	 $bool = version->parse("1.23_45") < version->parse("1.2345"); # TRUE

       See version::Internals for more details on "alpha" versions.

OBJECT METHODS
   is_alpha()
       True if and only	if the version object was created with a underscore,
       e.g.

	 version->parse('1.002_03')->is_alpha;	# TRUE
	 version->declare('1.2.3_4')->is_alpha;	# TRUE

   is_qv()
       True only if the	version	object is a dotted-decimal version, e.g.

	 version->parse('v1.2.0')->is_qv;	# TRUE
	 version->declare('v1.2')->is_qv;	# TRUE
	 qv('1.2')->is_qv;			# TRUE
	 version->parse('1.2')->is_qv;		# FALSE

   normal()
       Returns a string	with a standard	'normalized' dotted-decimal form with
       a leading-v and at least	3 components.

	version->declare('v1.2')->normal;  # v1.2.0
	version->parse('1.2')->normal;	   # v1.200.0

   numify()
       Returns a value representing the	object in a pure decimal form without
       trailing	zeroes.

	version->declare('v1.2')->numify;  # 1.002
	version->parse('1.2')->numify;	   # 1.200

   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.

	version->declare('v1.2')->stringify;	# v1.2
	version->parse('1.200')->stringify;	# 1.200
	version->parse(1.02_30)->stringify;	# 1.023

EXPORTED FUNCTIONS
   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:

	 use version 0.77 ();

   is_lax()
       (Not exported by	default)

       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.

   is_strict()
       (Not exported by	default)

       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.

AUTHOR
       John Peacock <jpeacock@cpan.org>

SEE ALSO
       version::Internals.

       perl.

perl v5.24.1			  2016-07-14			    version(3)

NAME | SYNOPSIS | DESCRIPTION | TYPES OF VERSION OBJECTS | DECLARING VERSIONS | PARSING AND COMPARING VERSIONS | OBJECT METHODS | EXPORTED FUNCTIONS | AUTHOR | SEE ALSO

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