Perl::Critic::Policy::ControlStructures::ProhibitPostfixControls
Conway discourages using postfix control structures (if, for, unless, until, while). 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.
if
for
unless
until
while
last
next
redo
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 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.
die
croak
confess
warn
carp
cluck
Jeffrey Ryan Thalhammer <thaljef@cpan.org>
Copyright (c) 2005-2007 Jeffrey Ryan Thalhammer. All rights reserved.
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cpanm
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