Perl::Critic::Policy::InputOutput::ProhibitBarewordFileHandles3pm

Write "open my $fh, q{<}, $filename;" instead of "open fh, q{<}, $filename;".

Affiliation

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

Overview

Using bareword symbols to refer to file handles is particularly evil because they are global, and you have no idea if that symbol already points to some other file handle. You can mitigate some of that risk by "local"izing the symbol first, but that's pretty ugly. Since Perl 5.6, you can use an undefined scalar variable as a lexical reference to an anonymous filehandle. Alternatively, see the IO::Handle or IO::File or FileHandle modules for an object-oriented approach.

    open FH, '<', $some_file;           #not ok
    open my $fh, '<', $some_file;       #ok
    my $fh = IO::File->new($some_file); #ok

There are three exceptions: STDIN, STDOUT and STDERR. These three standard filehandles are always package variables.

This policy also applies to the "sysopen" function as well.

Configuration

This Policy is not configurable except for the standard options.

Releases

10 releases since Debian 5.0 (Lenny); the text changed 9 times.

5.0
6.0
7
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Arch