Perl::Critic::Policy::Modules::RequireVersionVar3pm

Affiliation

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

Overview

Every Perl file (modules, libraries, and programs) should have a package-scoped $VERSION variable. The $VERSION allows clients to insist on a particular revision of your file like this:

    use SomeModule 2.4;  #Only loads version 2.4

This Policy scans your file for any package variable named $VERSION. I'm assuming that you are using "strict", so you'll have to declare it like one of these:

    our $VERSION = 1.0611;
    $MyPackage::VERSION = 1.061;
    use vars qw($VERSION);
    use version; our $VERSION = qv(1.0611);

Perl's version system does not recognize lexical variables such as

    my $VERSION = 1.0611;

so they are not accepted by this policy.

A common practice is to use the "$Revision$" keyword to automatically define the $VERSION variable like this:

    our ($VERSION) = '$Revision$' =~ m{ \$Revision: \s+ (\S+) }x;

Configuration

This Policy is not configurable except for the standard options.

Notes

Conway recommends using the "version" pragma instead of raw numbers or 'v-strings.' However, this Policy only insists that the $VERSION be defined somehow. I may try to extend this in the future.

To do

Add check that $VERSION is independently evaluatable. In particular, prohibit this:

    our $VERSION = $Other::Module::VERSION;

This doesn't work because PAUSE and other tools literally copy your version declaration out of your module and evaluates it in isolation, at which point there's nothing in "Other::Module", and so the $VERSION is undefined.