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 v5.20.2                                    Perl::Critic::Policy::Subroutines::ProhibitExcessComplexity(3pm)