.\" Automatically generated by Pod::Man 4.09 (Pod::Simple 3.35) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" Perl::Critic::Policy::ControlStructures::ProhibitPostfixControls \- Write "if($condition){ do_something() }" instead of "do_something() if $condition". .SH "AFFILIATION" .IX Header "AFFILIATION" This Policy is part of the core Perl::Critic distribution. .SH "DESCRIPTION" .IX Header "DESCRIPTION" Conway discourages using postfix control structures (\f(CW\*(C`if\*(C'\fR, \f(CW\*(C`for\*(C'\fR, \&\f(CW\*(C`unless\*(C'\fR, \f(CW\*(C`until\*(C'\fR, \f(CW\*(C`when\*(C'\fR, \f(CW\*(C`while\*(C'\fR) because they hide control flow. The \f(CW\*(C`unless\*(C'\fR and \f(CW\*(C`until\*(C'\fR controls are particularly evil because they lead to double-negatives that are hard to comprehend. The only tolerable usage of a postfix \f(CW\*(C`if\*(C'\fR/\f(CW\*(C`when\*(C'\fR is when it follows a loop break such as \f(CW\*(C`last\*(C'\fR, \f(CW\*(C`next\*(C'\fR, \f(CW\*(C`redo\*(C'\fR, or \f(CW\*(C`continue\*(C'\fR. .PP .Vb 2 \& 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 \ez >xms; # fine too \& } .Ve .SH "CONFIGURATION" .IX Header "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: \&\f(CW\*(C`if\*(C'\fR, \f(CW\*(C`for\*(C'\fR, \f(CW\*(C`unless\*(C'\fR, \f(CW\*(C`until\*(C'\fR, \f(CW\*(C`when\*(C'\fR, and/or \f(CW\*(C`while\*(C'\fR. An example of specifying allowed flow-control structures in a \&\fI.perlcriticrc\fR file: .PP .Vb 2 \& [ControlStructures::ProhibitPostfixControls] \& allow = for if until .Ve .PP By default, all postfix control keywords are prohibited. .PP The set of flow-control functions that are exempt from the restriction can also be configured with the 'flowcontrol' directive in your \&\fI.perlcriticrc\fR file: .PP .Vb 2 \& [ControlStructures::ProhibitPostfixControls] \& flowcontrol = warn die carp croak cluck confess goto exit .Ve .PP This is useful if you're using additional modules that add things like \&\f(CW\*(C`assert\*(C'\fR or \f(CW\*(C`throw\*(C'\fR. .SH "NOTES" .IX Header "NOTES" The \f(CW\*(C`die\*(C'\fR, \f(CW\*(C`croak\*(C'\fR, and \f(CW\*(C`confess\*(C'\fR functions are frequently used as flow-controls just like \f(CW\*(C`next\*(C'\fR or \f(CW\*(C`last\*(C'\fR. So this Policy does permit you to use a postfix \f(CW\*(C`if\*(C'\fR when the statement begins with one of those functions. It is also pretty common to use \f(CW\*(C`warn\*(C'\fR, \f(CW\*(C`carp\*(C'\fR, and \f(CW\*(C`cluck\*(C'\fR with a postfix \f(CW\*(C`if\*(C'\fR, so those are allowed too. .PP The \f(CW\*(C`when\*(C'\fR keyword was added to the language after Perl Best Practices was written. This policy treats \f(CW\*(C`when\*(C'\fR the same way it does \f(CW\*(C`if\*(C'\fR, i.e. it's allowed after flow-control constructs. Thanks to brian d foy for the inspiration . .SH "BUGS" .IX Header "BUGS" Look for the \f(CW\*(C`do {} while\*(C'\fR case and change the explanation to point to page 123 when it is found. \s-1RT\s0 #37905. .SH "AUTHOR" .IX Header "AUTHOR" Jeffrey Ryan Thalhammer .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright (c) 2005\-2011 Imaginative Software Systems. All rights reserved. .PP 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 \s-1LICENSE\s0 file included with this module.