Perl::Critic::Policy::InputOutput::ProhibitReadlineInForLoop - Write while( $line = <> ){...} instead of for(<>){...}.


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


Using the readline operator in a for or foreach loop is very slow. The iteration list of the loop creates a list context, which causes the readline operator to read the entire input stream before iteration even starts. Instead, just use a while loop, which only reads one line at a time.

  for my $line ( <$file_handle> ){ do_something($line) }      #not ok
  while ( my $line = <$file_handle> ){ do_something($line) }  #ok


This Policy is not configurable except for the standard options.


Jeffrey Ryan Thalhammer <>


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.