NAME

       Perl::Critic::Policy::ValuesAndExpressions::RequireConstantVersion - Require $VERSION to
       be a constant rather than a computed value.

AFFILIATION

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

DESCRIPTION

       The $VERSION variable of a module should be a simple constant - either a number, a single-
       quotish string, or a 'use version' object. In the latter case the 'use version;' must
       appear on the same line as the object construction.

       Computing the version has problems of various severities.

       The most benign violation is computing the version from (e.g.) a Subversion revision
       number:

           our ($VERSION) = q$REVISION: 42$ =~ /(\d+)/;

       The problem here is that the version is tied to a single repository. The code can not be
       moved to another repository (even of the same type) without changing its version, possibly
       in the wrong direction.

       This policy accepts v-strings ("v1.2.3" or just plain 1.2.3), since these are already
       flagged by Perl::Critic::Policy::ValuesAndExpressions::ProhibitVersionStrings.

CONFIGURATION

       The proper way to set a module's $VERSION to a "version" object is to "use version;" on
       the same line of code that assigns the value of $VERSION.  That way, ExtUtils::MakeMaker
       and Module::Build can extract the version when packaging the module for CPAN. By default,
       this policy declares an error if this is not done.

       Should you wish to allow version objects without loading the version module on the same
       line, add the following to your configuration file:

           [ValuesAndExpressions::RequireConstantVersion]
           allow_version_without_use_on_same_line = 1

CAVEATS

       There will be false negatives if the $VERSION appears on the left-hand side of a list
       assignment that assigns to more than one variable, or to "undef".

       There may be false positives if the $VERSION is assigned the value of a here document.
       This will probably remain the case until PPI::Token::HereDoc acquires the relevant
       portions of the PPI::Token::Quote interface.

       There will be false positives if $VERSION is assigned the value of a constant created by
       the Readonly module or the constant pragma, because the necessary infrastructure appears
       not to exist, and the author of the present module lacked the knowledge/expertise/gumption
       to put it in place.

       Currently the idiom

           our $VERSION = '1.005_05';
           $VERSION = eval $VERSION;

       will produce a violation on the second line of the example.

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 v5.20.2              Perl::Critic::Policy::ValuesAndExpressions::RequireConstantVersion(3pm)