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Perl::Critic::Policy::InputOutput::ProhibitExplicitStdin - Use "<>" or "<ARGV>" or a prompting module

Affiliation

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

Author

       Chris Dolan <cdolan@cpan.org>

Caveats

       Due to a bug in the current version of PPI (v1.119_03) and earlier, the readline operator is often
       misinterpreted as less-than and greater-than operators after a comma.  Therefore, this policy misses
       important cases like

         my $content = join '', <STDIN>;

       because it interprets that line as the nonsensical statement:

         my $content = join '', < STDIN >;

       When that PPI bug is fixed, this policy should start catching those violations automatically.

Configuration

       This Policy is not configurable except for the standard options.

Credits

       Initial development of this policy was supported by a grant from the Perl Foundation.

Description

       Perl has a useful magic filehandle called *ARGV that checks the command line and if there are any
       arguments, opens and reads those as files.  If there are no arguments, *ARGV behaves like *STDIN instead.
       This behavior is almost always what you want if you want to create a program that reads from "STDIN".
       This is often written in one of the following two equivalent forms:

         while (<ARGV>) {
           # ... do something with each input line ...
         }
         # or, equivalently:
         while (<>) {
           # ... do something with each input line ...
         }

       If you want to prompt for user input, try special purpose modules like IO::Prompt.

Name

       Perl::Critic::Policy::InputOutput::ProhibitExplicitStdin - Use "<>" or "<ARGV>" or a prompting module
       instead of "<STDIN>".

See Also