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.IX Title "Perl::Critic::Policy::InputOutput::ProhibitBarewordFileHandles 3pm"
.TH Perl::Critic::Policy::InputOutput::ProhibitBarewordFileHandles 3pm 2023-07-26 "perl v5.38.0" "User Contributed Perl Documentation"
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.SH NAME
Perl::Critic::Policy::InputOutput::ProhibitBarewordFileHandles \- Write "open my $fh, q{<}, $filename;" instead of "open FH, q{<}, $filename;".
.SH AFFILIATION
.IX Header "AFFILIATION"
This Policy is part of the core Perl::Critic
distribution.
.SH DESCRIPTION
.IX Header "DESCRIPTION"
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 \f(CW\*(C`local\*(C'\fRizing 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.
.PP
.Vb 3
\&    open FH, \*(Aq<\*(Aq, $some_file;           #not ok
\&    open my $fh, \*(Aq<\*(Aq, $some_file;       #ok
\&    my $fh = IO::File\->new($some_file); #ok
.Ve
.PP
There are three exceptions: STDIN, STDOUT and STDERR.  These three
standard filehandles are always package variables.
.PP
This policy also applies to the \f(CW\*(C`sysopen\*(C'\fR function as well.
.SH CONFIGURATION
.IX Header "CONFIGURATION"
This Policy is not configurable except for the standard options.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
IO::Handle
.PP
IO::File
.SH AUTHOR
.IX Header "AUTHOR"
Jeffrey Ryan Thalhammer <jeff@imaginative\-software.com>
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright (c) 2005\-2022 Imaginative Software Systems.  All rights reserved.
.PP
This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.