Perl::Critic::Policy::InputOutput::ProhibitBacktickOperators - Discourage stuff like @files = `ls $directory`.
This Policy is part of the core Perl::Critic distribution.
Backticks are super-convenient, especially for CGI programs, but I find that they make a lot of noise by filling up STDERR with messages when they fail. I think its better to use IPC::Open3 to trap all the output and let the application decide what to do with it.
use IPC::Open3 'open3';
$SIG{CHLD} = 'IGNORE';
@output = `some_command`; #not ok
my ($writer, $reader, $err);
open3($writer, $reader, $err, 'some_command'); #ok;
@output = <$reader>; #Output here
@errors = <$err>; #Errors here, instead of the console
Alternatively, if you do want to use backticks, you can restrict checks to void contexts by adding the following to your .perlcriticrc file:
[InputOutput::ProhibitBacktickOperators] only_in_void_context = 1
The purpose of backticks is to capture the output of an external
command. Use of them in a void context is likely a bug. If the
output isn't actually required, system() should be used. Otherwise
assign the result to a variable.
`some_command`; #not ok $output = `some_command`; #ok @output = `some_command`; #ok
This policy also prohibits the generalized form of backticks seen as
qx{}.
See perlipc for more discussion on using wait() instead of
$SIG{CHLD} = 'IGNORE'.
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.