NAME
    CPAN::Meta::Requirements - a set of version requirements for a CPAN dist

VERSION
    version 2.144

SYNOPSIS
      use CPAN::Meta::Requirements;

      my $build_requires = CPAN::Meta::Requirements->new;

      $build_requires->add_minimum('Library::Foo' => 1.208);

      $build_requires->add_minimum('Library::Foo' => 2.602);

      $build_requires->add_minimum('Module::Bar'  => 'v1.2.3');

      $METAyml->{build_requires} = $build_requires->as_string_hash;

DESCRIPTION
    A CPAN::Meta::Requirements object models a set of version constraints
    like those specified in the META.yml or META.json files in CPAN
    distributions, and as defined by CPAN::Meta::Spec. It can be built up by
    adding more and more constraints, and it will reduce them to the
    simplest representation.

    Logically impossible constraints will be identified immediately by
    thrown exceptions.

METHODS
  new
      my $req = CPAN::Meta::Requirements->new;

    This returns a new CPAN::Meta::Requirements object. It takes an optional
    hash reference argument. Currently, only one key is supported:

    *   "bad_version_hook" -- if provided, when a version cannot be parsed
        into a version object, this code reference will be called with the
        invalid version string as first argument, and the module name as
        second argument. It must return a valid version object.

    All other keys are ignored.

  add_minimum
      $req->add_minimum( $module => $version );

    This adds a new minimum version requirement. If the new requirement is
    redundant to the existing specification, this has no effect.

    Minimum requirements are inclusive. $version is required, along with any
    greater version number.

    This method returns the requirements object.

  add_maximum
      $req->add_maximum( $module => $version );

    This adds a new maximum version requirement. If the new requirement is
    redundant to the existing specification, this has no effect.

    Maximum requirements are inclusive. No version strictly greater than the
    given version is allowed.

    This method returns the requirements object.

  add_exclusion
      $req->add_exclusion( $module => $version );

    This adds a new excluded version. For example, you might use these three
    method calls:

      $req->add_minimum( $module => '1.00' );
      $req->add_maximum( $module => '1.82' );

      $req->add_exclusion( $module => '1.75' );

    Any version between 1.00 and 1.82 inclusive would be acceptable, except
    for 1.75.

    This method returns the requirements object.

  exact_version
      $req->exact_version( $module => $version );

    This sets the version required for the given module to *exactly* the
    given version. No other version would be considered acceptable.

    This method returns the requirements object.

  version_range_for_module
      $req->version_range_for_module( $another_req_object );

  add_requirements
      $req->add_requirements( $another_req_object );

    This method adds all the requirements in the given
    CPAN::Meta::Requirements object to the requirements object on which it
    was called. If there are any conflicts, an exception is thrown.

    This method returns the requirements object.

  accepts_module
      my $bool = $req->accepts_module($module => $version);

    Given an module and version, this method returns true if the version
    specification for the module accepts the provided version. In other
    words, given:

      Module => '>= 1.00, < 2.00'

    We will accept 1.00 and 1.75 but not 0.50 or 2.00.

    For modules that do not appear in the requirements, this method will
    return true.

  clear_requirement
      $req->clear_requirement( $module );

    This removes the requirement for a given module from the object.

    This method returns the requirements object.

  requirements_for_module
      $req->requirements_for_module( $module );

    This returns a string containing the version requirements for a given
    module in the format described in CPAN::Meta::Spec or undef if the given
    module has no requirements. This should only be used for informational
    purposes such as error messages and should not be interpreted or used
    for comparison (see "accepts_module" instead).

  structured_requirements_for_module
      $req->structured_requirements_for_module( $module );

    This returns a data structure containing the version requirements for a
    given module or undef if the given module has no requirements. This
    should not be used for version checks (see "accepts_module" instead).

    Added in version 2.134.

  required_modules
    This method returns a list of all the modules for which requirements
    have been specified.

  clone
      $req->clone;

    This method returns a clone of the invocant. The clone and the original
    object can then be changed independent of one another.

  is_simple
    This method returns true if and only if all requirements are inclusive
    minimums -- that is, if their string expression is just the version
    number.

  is_finalized
    This method returns true if the requirements have been finalized by
    having the "finalize" method called on them.

  finalize
    This method marks the requirements finalized. Subsequent attempts to
    change the requirements will be fatal, *if* they would result in a
    change. If they would not alter the requirements, they have no effect.

    If a finalized set of requirements is cloned, the cloned requirements
    are not also finalized.

  as_string_hash
    This returns a reference to a hash describing the requirements using the
    strings in the CPAN::Meta::Spec specification.

    For example after the following program:

      my $req = CPAN::Meta::Requirements->new;

      $req->add_minimum('CPAN::Meta::Requirements' => 0.102);

      $req->add_minimum('Library::Foo' => 1.208);

      $req->add_maximum('Library::Foo' => 2.602);

      $req->add_minimum('Module::Bar'  => 'v1.2.3');

      $req->add_exclusion('Module::Bar'  => 'v1.2.8');

      $req->exact_version('Xyzzy'  => '6.01');

      my $hashref = $req->as_string_hash;

    $hashref would contain:

      {
        'CPAN::Meta::Requirements' => '0.102',
        'Library::Foo' => '>= 1.208, <= 2.206',
        'Module::Bar'  => '>= v1.2.3, != v1.2.8',
        'Xyzzy'        => '== 6.01',
      }

  add_string_requirement
      $req->add_string_requirement('Library::Foo' => '>= 1.208, <= 2.206');
      $req->add_string_requirement('Library::Foo' => v1.208);

    This method parses the passed in string and adds the appropriate
    requirement for the given module. A version can be a Perl "v-string". It
    understands version ranges as described in the "Version Ranges" in
    CPAN::Meta::Spec. For example:

    1.3
    >= 1.3
    <= 1.3
    == 1.3
    != 1.3
    > 1.3
    < 1.3
    >= 1.3, != 1.5, <= 2.0
        A version number without an operator is equivalent to specifying a
        minimum (">="). Extra whitespace is allowed.

  from_string_hash
      my $req = CPAN::Meta::Requirements->from_string_hash( \%hash );
      my $req = CPAN::Meta::Requirements->from_string_hash( \%hash, \%opts );

    This is an alternate constructor for a CPAN::Meta::Requirements object.
    It takes a hash of module names and version requirement strings and
    returns a new CPAN::Meta::Requirements object. As with
    add_string_requirement, a version can be a Perl "v-string". Optionally,
    you can supply a hash-reference of options, exactly as with the "new"
    method.

SUPPORT
  Bugs / Feature Requests
    Please report any bugs or feature requests through the issue tracker at
    <https://github.com/Perl-Toolchain-Gang/CPAN-Meta-Requirements/issues>.
    You will be notified automatically of any progress on your issue.

  Source Code
    This is open source software. The code repository is available for
    public review and contribution under the terms of the license.

    <https://github.com/Perl-Toolchain-Gang/CPAN-Meta-Requirements>

      git clone https://github.com/Perl-Toolchain-Gang/CPAN-Meta-Requirements.git

AUTHORS
    *   David Golden <dagolden@cpan.org>

    *   Ricardo Signes <cpan@semiotic.systems>

CONTRIBUTORS
    *   Ed J <mohawk2@users.noreply.github.com>

    *   Graham Knop <haarg@haarg.org>

    *   Karen Etheridge <ether@cpan.org>

    *   Leon Timmermans <fawaka@gmail.com>

    *   Paul Howarth <paul@city-fan.org>

    *   Philippe Bruhat (BooK) <book@cpan.org>

    *   Ricardo Signes <rjbs@semiotic.systems>

    *   robario <webmaster@robario.com>

    *   Tatsuhiko Miyagawa <miyagawa@bulknews.net>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2010 by David Golden and Ricardo Signes.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

