Perl::Critic::PoPerl::Critic::Policy::Modules::ProhibitExcessMainComplexity(3)NAMEPerl::Critic::Policy::Modules::ProhibitExcessMainComplexity - Minimize
complexity in code that is outside of 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 block of code. This Policy approximates the McCabe
score by summing the number of conditional statements and operators
within a block of code. 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.
Whereas Perl::Critic::Policy::Subroutines::ProhibitExcessComplexity
scores the complexity of each subroutine, this Policy scores the total
complexity of all the code that is outside of any subroutine
declaration.
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 score can be set with the "max_mccabe"
configuration item. If the sum of all code outside any subroutine has
a McCabe score higher than this number, it will generate a Policy
violation. The default is 20. An example section for a .perlcriticrc:
[Modules::ProhibitExcessMainComplexity]
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.
SEE ALSO
Perl::Critic::Policy::Subroutines::ProhibitExcessComplexity
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 v5.14.1Perl::Critic::Policy::Modules::ProhibitExcessMainComplexity(3)
