From perldoc perlopentut: 
Indirect Filehandles

"open"'s first argument can be a reference to a
filehandle.  As of perl 5.6.0, if the argument is
uninitialized, Perl will automatically create a
filehandle and put a reference to it in the first
argument, like so:

  open( my $in, $infile )
    or die "Couldn't read $infile: $!";
  while ( <$in> ) {
    # do something with $_
  }
  close $in;
It doesn't get much more dynamic than that.

In reply to Re: Dynamic File Handles by trammell
in thread Dynamic File Handles by Anonymous Monk

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