phpman > man > version(3perl)

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:

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

    * Always use a leading-v

    * 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.

    * 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.

    * 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 < 0.94; # TRUE since 0.94 is v0.940.0

    Always comparing to a version object will help avoid surprises:

      $bool = $v1 < version->parse("v0.94.0"); # FALSE

    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.

     version->declare('v1.2')->numify;  # 1.002000
     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;     # 1.2
     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 AT cpan.org>

SEE ALSO
    version::Internals.

    perl.