Jeffrey Ryan Thalhammer > Perl-Critic-1.118 > Perl::Critic::Policy::InputOutput::ProhibitTwoArgOpen

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Module Version: 1.118   Source   Latest Release: Perl-Critic-1.122

NAME ^

Perl::Critic::Policy::InputOutput::ProhibitTwoArgOpen - Write open $fh, q{<}, $filename; instead of open $fh, "<$filename";.

AFFILIATION ^

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

DESCRIPTION ^

The three-argument form of open (introduced in Perl 5.6) prevents subtle bugs that occur when the filename starts with funny characters like '>' or '<'. The IO::File module provides a nice object-oriented interface to filehandles, which I think is more elegant anyway.

  open( $fh, '>output.txt' );          # not ok
  open( $fh, q{>}, 'output.txt' );     # ok

  use IO::File;
  my $fh = IO::File->new( 'output.txt', q{>} ); # even better!

It's also more explicitly clear to define the input mode of the file, as in the difference between these two:

  open( $fh, 'foo.txt' );       # BAD: Reader must think what default mode is
  open( $fh, '<', 'foo.txt' );  # GOOD: Reader can see open mode

This policy will not complain if the file explicitly states that it is compatible with a version of perl prior to 5.6 via an include statement, e.g. by having require 5.005 in it.

CONFIGURATION ^

This Policy is not configurable except for the standard options.

NOTES ^

There are two cases in which you are forced to use the two-argument form of open. When re-opening STDIN, STDOUT, or STDERR, and when doing a safe pipe open, as described in perlipc.

SEE ALSO ^

IO::Handle

IO::File

AUTHOR ^

Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>

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.

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