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Perl::CritiPerl::CritiUseroContributedoPerluDocumentationbitPostfixControls(3)

NAME
       Perl::Critic::Policy::ControlStructures::ProhibitPostfixControls	-
       Write "if($condition){ do_something() }"	instead	of "do_something() if
       $condition".

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

DESCRIPTION
       Conway discourages using	postfix	control	structures ("if", "for",
       "unless", "until", "when", "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"/"when"	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

	       next when m< 0 \z >xms;		   # fine too
	   }

CONFIGURATION
       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", "when", 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

       This is useful if you're	using additional modules that add things like
       "assert"	or "throw".

NOTES
       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.

       The "when" keyword was added to the language after Perl Best Practices
       was written.  This policy treats	"when" the same	way it does "if", i.e.
       it's allowed after flow-control constructs.  Thanks to brian d foy for
       the inspiration <http://www.effectiveperlprogramming.com/blog/543>.

BUGS
       Look for	the "do	{} while" case and change the explanation to point to
       page 123	when it	is found.  RT #37905.

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 v5.24.Perl::Critic::Policy::ControlStructures::ProhibitPostfixControls(3)

NAME | AFFILIATION | DESCRIPTION | CONFIGURATION | NOTES | BUGS | AUTHOR | COPYRIGHT

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