---
name: "Perl::Critic::Policy::ValuesAndExpressions::ProhibitComplexVersion"
section: "3pm"
platform: "linux"
package: "perl-perl-critic"
version: "1.156-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Perl::Critic::Policy::ValuesAndExpressions::ProhibitComplexVersion"
---

# Perl::Critic::Policy::ValuesAndExpressions::ProhibitComplexVersion(3pm)

Prohibit version values from outside the module.

## 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) 2009-2023 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.