Lastly, I think you can use a typeglob. But I'm not sure how, and it'll be ugly.

Depends on your definition of ugly ;-)

It's not difficult either - taking up on your example:

sub foo {
  local *FILE;
  open FILE, "file.txt";
  bar(*FILE);
}
sub bar {
  my $file = shift;
  my @lines = <$file>;
  # do something here
}
[download]

Your alternative that's using the lexical variable as a filehandle is still the best, imho, but compared to not passing it and relying on the global variable, the typeglob approach is surely better - unless the script is very short and trivially simple. Btw, note my use of local to avoid clobbering the global filehandle FILE.

-- Hofmator