The three-argument form of open (introduced in Perl 5.6) prevents subtle bugs that occur when the filename starts with funny characters like '>' or '<'. The the IO::File manpage module provides a nice object-oriented interface to filehandles, which I think is more elegant anyway.

  open( $fh, '>output.txt' );          # not ok
  open( $fh, q{>}, 'output.txt' );     # ok
  use IO::File;
  my $fh = IO::File->new( 'output.txt', q{>} ); # even better!

It's also more explicitly clear to define the input mode of the file, as in the difference between these two:

  open( $fh, 'foo.txt' );       # BAD: Reader must think what default mode is
  open( $fh, '<', 'foo.txt' );  # GOOD: Reader can see open mode


The only time you should use the two-argument form is when you re-open STDIN, STDOUT, or STDERR. But for now, this Policy doesn't provide that loophole.


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.