noble (3) Perl::Critic::Policy::Community::WhileDiamondDefaultAssignment.3pm.gz

Provided by: libperl-critic-community-perl_1.0.3-1_all bug

NAME
       Perl::Critic::Policy::Community::WhileDiamondDefaultAssignment - Don't use while with implicit assignment
       to $_


DESCRIPTION
       The diamond operator "<>" (or "<<>>"), and functions "readline()", "readdir()", and "each()" are extra
       magical in a while condition: if it is the only thing in the condition, it will assign its result to $_,
       but it does not localize $_ to the while loop. (Note, this also applies to a "for (;<>;)" construct.)
       This can unintentionally confuse outer loops that are already using $_ to iterate. In addition, using $_
       at all means that your loop can get confused by other code which does not politely localize its usage of
       the global variable. To avoid these possibilities, assign the result of the diamond operator or these
       functions to an explicit lexical variable.

         while (<$fh>) { ... }                   # not ok
         while (<<>>) { ... }                    # not ok
         ... while <STDIN>;                      # not ok
         for (;<>;) { ... }                      # not ok
         while (readline $fh) { ... }            # not ok
         while (readdir $dh) { ... }             # not ok

         while (my $line = <$fh>) { ... }        # ok
         while (my $line = <<>>) { ... }         # ok
         ... while $line = <STDIN>;              # ok
         for (;my $line = <>;) { ... }           # ok
         while (my $line = readline $fh) { ... } # ok
         while (my $dir = readdir $dh) { ... }   # ok


AFFILIATION
       This policy is part of Perl::Critic::Community.


CONFIGURATION
       This policy is not configurable except for the standard options.


AUTHOR
       Dan Book, "dbook@cpan.org"


       Copyright 2015, Dan Book.

       This library is free software; you may redistribute it and/or modify it under the terms of the Artistic
       License version 2.0.


SEE ALSO
       Perl::Critic

perl v5.34.0                                 Perl::Critic::Policy::Community::WhileDiamondDefaultAssignment(3pm)