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https://github.com/jonasbn/perl-critic-policy-inputoutput-prohibithighprecedentlogicaloperatorerrorhandling

Perl::Critic policy, prohibiting logical error handling in open statements
https://github.com/jonasbn/perl-critic-policy-inputoutput-prohibithighprecedentlogicaloperatorerrorhandling

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Perl::Critic policy, prohibiting logical error handling in open statements

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README 

        
# 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](https://metacpan.org/pod/autodie) can be used.



# CONFIGURATION AND ENVIRONMENT



This policy is not configurable at this time. Please see the TODO ["section"](#section).



# INCOMPATIBILITIES



Do note that this policy conflicts with the policy:



- [Perl::Critic::Policy::CodeLayout::ProhibitParensWithBuiltins](https://metacpan.org/pod/Perl::Critic::Policy::CodeLayout::ProhibitParensWithBuiltins)



# BUGS AND LIMITATIONS



This distribution holds no known limitations or bugs at this time, please refer to the [the issue listing on GitHub](https://github.com/jonasbn/perl-critic-policy-regularexpressions-requiredefault/issues) for more up to date information.



# BUG REPORTING



Please report bugs via [GitHub](https://github.com/jonasbn/perl-critic-policy-regularexpressions-requiredefault/issues).



# 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](https://metacpan.org/pod/release/JESSE/perl-5.14.0/pod/perl.pod) for developing the distribution, which relies on [Dist::Zilla](http://dzil.org/). 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](https://metacpan.org/pod/Carp), in core since Perl 5.

- [Readonly](https://metacpan.org/pod/Readonly)

- [Perl::Critic::Policy](https://metacpan.org/pod/Perl::Critic::Policy)

- [Perl::Critic::Utils](https://metacpan.org/pod/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`.



- Please see [the issue listing on GitHub](https://github.com/jonasbn/perl-critic-policy-regularexpressions-requiredefault/issues)



# SEE ALSO



- [Blog post on Perl Hacks: A Subtle Bug](https://perlhacks.com/2019/01/a-subtle-bug/) by Dave Cross [@davorg](https://twitter.com/davorg)

- [Same Blog post on Medium: A Subtle Bug](https://culturedperl.com/a-subtle-bug-c9982f681cb8) by Dave Cross [@davorg](https://twitter.com/davorg)

- [Perl::Critic](https://metacpan.org/pod/Perl::Critic)



# MOTIVATION



The motivation for this Perl::Critic policy came from a [Blog post on Perl Hacks: A Subtle Bug](https://perlhacks.com/2019/01/a-subtle-bug/) by Dave Cross [@davorg](https://twitter.com/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) 



# ACKNOWLEDGEMENTS



- [Dave Cross (@davorg)](https://twitter.com/davorg) / [DAVECROSS](https://metacpan.org/author/DAVECROSS) for the blog post sparking the idea for this policy, see link to blog post under ["MOTIVATION"](#motivation) or ["REFERENCES"](#references)

- [Ed Sabol](https://github.com/esabol) for taking the time to correct some bad punctuation

- [Nathan Mills](https://github.com/Quipyowert2) for contributing to this policy, documenting and testing two-argument `open`



# 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