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 localizing 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 the IO::Handle manpage or the IO::File manpage or the FileHandle manpage 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.


the IO::Handle manpage

the IO::File manpage


Jeffrey Ryan Thalhammer <thaljef@cpan.org>


Copyright (C) 2005-2007 Jeffrey Ryan Thalhammer. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.