>This and other RFCs are available on the web at
> http://dev.perl.org/rfc/
>=head1 TITLE
>Eliminate bareword filehandles.
"Eliminate" is such a strong word. You're saying that we can't
use STDIN, STDOUT, STDERR, ARGV, or DATA anymore? Heck, some people
still use stdin and stdout! :-)
>=head1 ABSTRACT
>Now that scalars (objects) can be used for filehandles, the bareword form
>should be eliminated.
If true, doesn't that argument hold true for functions, too? If
all non-method functions were stored in only in variables, I guarantee
you that it would be rather harder to call a non-method function
as though it were a method.
>=head1 DESCRIPTION
>The venerable bareword form of the filehandle leads to code that is
>unnecessarily abstruse given that they can now be stored in
>scalars. Bareword filehandles are not lexical, and require the use of
>typeglobs and C<local> to pass them to subroutines, concepts unnecessarily
>advanced for such a beginner-type operation.
It does?
sub p {
my $fh = shift;
print $fh "got it\n";
}
p(STDOUT);
Of course, that's a bit dicey because STDOUT is omniglobal. You
could pass it as
p(*FH);
instead, and the function's definition doesn't change. What I tell
people is that if they want, they can just pretend, even though
it's not quite true, that * is the type symbol for a filehandle
at least when it comes to passing it or storing in somewhere.
This works out quite well.
Of course, with prototypes, even this is unneeded:
sub p(*) {
my $fh = shift;
print $fh "got it\n";
}
p(FH);
Filehandles really aren't that spooky anymore.
sub getfh {
return open(my $fh, "+< /dev/null") && $fh;
}
A simple unsubscripted scalar can virtually always be used to hold
a potentially package-qualified subroutine name, filehandle name,
a directory handle name, or a format handle name, and that scalar
used in lieu of those names (if unqualified, they're usually
package-relative, of course). These are called "indirect function calls"
or "indirect filehandles", etc. You can even do it with a method name, to
invoke an indirected method call (well, if you use the arrow syntax).
Indirections seem kind of nice.
--tom
