John Tobey wrote:
> The Perl 5 (and older) behavior may preclude some optimizations.
I can't think of any optimizations @_ assignment precludes.
If we don't analyze dataflow to figure out if a sub modifies its
args, then we just assume it will.
Is this just a style issue? Why would you allow it with a
prototyped function? The following is fully prototyped and
still hard to optimize without dataflow:
sub make_setter ($) {
my $x = \$_[0];
sub { $$x = $_[0] }
}
{
my $x = 1;
my $f = make_setter($x);
print "x = $x\n";
&$f(2);
print "x = $x\n";
}
Or do you mean that only prototypes taking a reference are
allowed to modify their arguments? So make_setter becomes
sub make_setter (\$) {
my($x) = @_;
sub { $$x = $_[0] }
}
How would you do vararg subs that have in/out args?
- Ken
