Perl::Critic::Policy::ControlStructures::ProhibitPostfixControls - Write if($condition){ do_something() } instead of do_something() if $condition.
This Policy is part of the core Perl::Critic distribution.
Conway discourages using postfix control structures (if, for,
unless, until, while) because they hide control flow. The
unless and until controls are particularly evil because they
lead to double-negatives that are hard to comprehend. The only
tolerable usage of a postfix if is when it follows a loop break
such as last, next, redo, or continue.
do_something() if $condition; #not ok
if($condition){ do_something() } #ok
do_something() while $condition; #not ok
while($condition){ do_something() } #ok
do_something() unless $condition; #not ok
do_something() unless ! $condition; #really bad
if(! $condition){ do_something() } #ok
do_something() until $condition; #not ok
do_something() until ! $condition; #really bad
while(! $condition){ do_something() } #ok
do_something($_) for @list; #not ok
LOOP:
for my $n (0..100){
next if $condition; #ok
last LOOP if $other_condition; #also ok
}
A set of constructs to be ignored by this policy can specified by
giving a value for 'allow' of a string of space-delimited keywords:
if, for, unless, until, and/or while. An example of
specifying allowed flow-control structures in a .perlcriticrc file:
[ControlStructures::ProhibitPostfixControls] allow = for if until
By default, all postfix control keywords are prohibited.
The set of flow-control functions that are exempt from the restriction can also be configured with the 'flowcontrol' directive in your .perlcriticrc file:
[ControlStructures::ProhibitPostfixControls] flowcontrol = warn die carp croak cluck confess goto exit
The die, croak, and confess functions are frequently used as
flow-controls just like next or last. So this Policy does
permit you to use a postfix if when the statement begins with one
of those functions. It is also pretty common to use warn, carp,
and cluck with a postfix if, so those are allowed too.
Jeffrey Ryan Thalhammer <thaljef@cpan.org>
Copyright (c) 2005-2008 Jeffrey Ryan Thalhammer. 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.