/ 
Perl-Critic-Policy-InputOutput-ProhibitHighPrecedentLogicalOperatorErrorHandling-0.02
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/ Perl::Critic::Policy::InputOutput::ProhibitHighPrecedentLogicalOperatorErrorHandling

NAME

Perl::Critic::Policy::InputOutput::ProhibitHighPrecedentLogicalOperatorErrorHandling - prohibits logical error handling in open statements

VERSION

This documentation describes version: 0.02

AFFILIATION

This policy has no affiliation

DESCRIPTION

This policy addresses an anti-pattern and possible bug. If you use open combined with the high precedence logical or operator || for error handling.

If the file parameter is pointing to a non-existent file, the use of a high precedence logical operator ||, does not short-cut as expected. This implies that the bug only is present if the file does not exist. If the file exists, but cannot be opened the error handling is not working as expected.

open my $fh, '<', $file
        || die "Can't open '$file': $!"; # not okay

open(my $fh, '<', $file)
    || die "Can't open '$file': $!"; # okay

open my $fh, '<', $file
    or die "Can't open '$file': $!"; # okay

open my $fh, "<$file"
        || die "Can't open '$file': $!"; # not okay

open(my $fh, "<$file")
    || die "Can't open '$file': $!"; # okay

open my $fh, "<$file"
    or die "Can't open '$file': $!"; # okay

The remedy is to use parentheses for open or the lower precedence logical operator or.

Alternatively autodie can be used,

CONFIGURATION AND ENVIRONMENT

This policy is not configurable at this time. Please see the TODO "section".

INCOMPATIBILITIES

Do note that this policy conflicts with the policy:

BUGS AND LIMITATIONS

This distribution holds no known limitations or bugs at this time, please refer to the the issue listing on GitHub for more up to date information.

BUG REPORTING

Please report bugs via GitHub.

TEST AND QUALITY

This distribution aims to adhere to the Perl::Critic::Policy standards and Perl best practices and recommendations.

DEPENDENCIES AND REQUIREMENTS

This distribution requires:

  • Perl 5.6.0 syntactically for the actual implementation

  • Perl 5.14 for developing the distribution, which relies on Dist::Zilla. The features on which this policy relies, where introduced in Perl 5.14, but this does not make for an actual requirement for the policy only the recommendations it imposes.

  • Carp, in core since Perl 5.

  • Readonly

  • Perl::Critic::Policy

  • Perl::Critic::Utils

Please see the listing in the file: cpanfile, included with the distribution for a complete listing and description for configuration, test and development.

TODO

Ideas and suggestions for improvements and new features are listed in GitHub and are marked as enhancement.

SEE ALSO

MOTIVATION

The motivation for this Perl::Critic policy came from a Blog post on Perl Hacks: A Subtle Bug by Dave Cross @davorg

In the blog post Dave demonstrates a very subtle bug, which I think many Perl programmers have been or could be bitten by. But instead of searching through the code as a one time activity, I think this would do better as a Perl::Critic policy, so if the bug a some point was reintroduced in the code base it would be caught by Perl::Critic, if you use Perl::Critic that is - and you do use Perl::Critic right?

AUTHOR

  • Jonas Brømsø (jonasbn) <jonasbn@cpan.org>

ACKNOWLEDGEMENTS

LICENSE AND COPYRIGHT

Perl::Critic::Policy::InputOutput::ProhibitHighPrecedentLogicalOperatorErrorHandling is (C) by jonasbn 2019-2021

Perl::Critic::Policy::InputOutput::ProhibitHighPrecedentLogicalOperatorErrorHandling is released under the Artistic License 2.0

Please see the LICENSE file included with the distribution of this module