NAME

       Perl::Critic::Policy::Subroutines::ProhibitExcessComplexity - Minimize complexity by
       factoring code into smaller subroutines.

AFFILIATION

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

DESCRIPTION

       All else being equal, complicated code is more error-prone and more expensive to maintain
       than simpler code.  The first step towards managing complexity is to establish formal
       complexity metrics.  One such metric is the McCabe score, which describes the number of
       possible paths through a subroutine.  This Policy approximates the McCabe score by summing
       the number of conditional statements and operators within a subroutine.  Research has
       shown that a McCabe score higher than 20 is a sign of high-risk, potentially untestable
       code.  See <http://en.wikipedia.org/wiki/Cyclomatic_complexity> for some discussion about
       the McCabe number and other complexity metrics.

       The usual prescription for reducing complexity is to refactor code into smaller
       subroutines.  Mark Dominus book "Higher Order Perl" also describes callbacks, recursion,
       memoization, iterators, and other techniques that help create simple and extensible Perl
       code.

CONFIGURATION

       The maximum acceptable McCabe can be set with the "max_mccabe" configuration item.  Any
       subroutine with a McCabe score higher than this number will generate a policy violation.
       The default is 20.  An example section for a .perlcriticrc:

         [Subroutines::ProhibitExcessComplexity]
         max_mccabe = 30

NOTES

         "Everything should be made as simple as possible, but no simpler."

                                                         -- Albert Einstein

       Complexity is subjective, but formal complexity metrics are still incredibly valuable.
       Every problem has an inherent level of complexity, so it is not necessarily optimal to
       minimize the McCabe number.  So don't get offended if your code triggers this Policy.
       Just consider if there might be a simpler way to get the job done.

AUTHOR

       Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>

COPYRIGHT

       Copyright (c) 2005-2011 Imaginative Software Systems.  All rights reserved.

       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::Subroutines::ProhibitExcessComplexity(3pm)