NAME

       Perl::Critic::Policy::ValuesAndExpressions::ProhibitComplexVersion - Prohibit version
       values from outside the module.

AFFILIATION

       This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

       One tempting way to keep a group of related modules at the same version number is to have
       all of them import the version number from a designated module. For example, module
       "Foo::Master" could be the version master for the "Foo" package, and all other modules
       could use its $VERSION by

           use Foo::Master; our $VERSION = $Foo::Master::VERSION;

       This turns out not to be a good idea, because all sorts of unintended things can happen -
       anything from unintended version number changes to denial-of-service attacks (since
       "Foo::Master" is executed by the 'use').

       This policy examines statements that assign to $VERSION, and declares a violation under
       two circumstances: first, if that statement uses a fully-qualified symbol that did not
       originate in a package declared in the file; second if there is a "use" statement on the
       same line that makes the assignment.

       By default, an exception is made for "use version;" because of its recommendation by Perl
       Best Practices. See the "forbid_use_version" configuration variable if you do not want an
       exception made for "use version;".

CONFIGURATION

       The construction

           use version; our $VERSION = qv('1.2.3');

       is exempt from this policy by default, because it is recommended by Perl Best Practices.
       Should you wish to identify "use version;" as a violation, add the following to your
       perlcriticrc file:

           [ValuesAndExpressions::ProhibitComplexVersion]
           forbid_use_version = 1

CAVEATS

       This code assumes that the hallmark of a violation is a 'use' on the same line as the
       $VERSION assignment, because that is the way to have it seen by
       ExtUtils::MakeMaker->parse_version(). Other ways to get a version value from outside the
       module can be imagined, and this policy is currently oblivious to them.

AUTHOR

       Thomas R. Wyant, III wyant at cpan dot org

COPYRIGHT

       Copyright (c) 2009-2011 Tom Wyant.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.  The full text of this license can be found in the LICENSE file
       included with this module.

perl v5.18.1              Perl::Critic::Policy::ValuesAndExpressions::ProhibitComplexVersion(3pm)