Perl::...ntrols(3pm)

okay bestie, this is Perl::...ntrols(3pm) from User Contributed Perl Documentation — the Perl::Critic policy page that's about to make your postfix ifs think twice 💅✨

✨ NAME ✨

Perl::Critic::Policy::ControlStructures::ProhibitPostfixControls is the policy, and its whole vibe is: write if($condition){ do_something() } instead of do_something() if $condition. 🎀

🦋 AFFILIATION 🦋

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

💖 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. Here's 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> — iconic.

🌸 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. 💖

---

okay, that's the whole page, bestie 💖 this one is from perl v5.42.0, dated 2024-10-23, and the manual name is Perl::...ntrols(3pm) — periodt ✨