You can pass a bareword filehandle to Perl functions like eof, and you''d like to write similar subroutines of your own.
Use the Symbol module''s qualify_to_ref in conjunction with a * prototype on the subroutine:
use Symbol qw(qualify_to_ref);
sub my_eof (*) {
my $handle = shift;
$handle = qualify_to_ref($handle, caller( ));
# use $handle
}The * prototype tells Perl that the function expects a bareword filehandle as its argument. This lets you call the function like so:
my_eof(HANDLE);
This works even when use strict ''subs'' is in effect. The function receives a string as its argument, though. To safely use the argument as a filehandle, you need the Symbol module to turn it into a reference to a typeglob. And since typeglob refs can be used wherever you''d use named filehandles, store that reference in a scalar variable and use the variable as an indirect filehandle within your subroutine.
If you pass in a filehandle that is already a reference to a typeglob, like those autovivified by open, Perl and qualify_to_ref still do the right thing:
open(my $fh, "<", $filename) or die; my_eof($fh);
This technique is used in Recipe 7.23.
The documentation for the standard module Symbol (also in Chapter 32 of Programming Perl); the "Prototypes" section in the perlsub(1) manpage (also in Chapter 6 of Programming Perl); Recipe 7.23