On Wed, 20 Nov 2002, Pense, Joachim wrote:
> Bart Lateur [mailto:[EMAIL PROTECTED]] wrote:
> (Mittwoch, 20. November 2002 11:43)
>
> >On Wed, 20 Nov 2002 04:10:02 -0600, Steven Lembark wrote:
> >
> >>sub commify
> >>{
> >> my ( $max, $sep, $end ) = ( shift, shift, shift );
> > ...
> >>}
> >
> >Wow! Hold it! Am I the only one who finds this absurd? More than one
> >shift on the same array in one single expressing, sounds like bad style
> >to me. Comments?
>
> In one of my programs, this would be
>
> sub commify {
> my $max = shift;
> my $sep = shift;
> my $end = shift;
>
> ...
> }
>
> better or even worse in your view?
Better, but only if it makes sense to conditionally take values off the
calling stack, like this contrived example:
sub foo {
my $type = shift;
my $arg1 = shift;
my $arg2 = 0;
if ($type == 'APIv2') {
$arg2 = shift;
}
return $arg1 + $arg2;
}
A variation of this would be if, depending on the type, you might want
different names for a given element on the calling stack:
sub foo {
my $type = shift;
my $arg1 = shift;
if ($type == 'APIv2') {
my $adder = shift;
return $arg1 + $adder
} elsif ($type == 'APIv3') {
my $subtractor = shift;
return $arg1 - $subtractor;
}
return $arg1;
}
You might also do something like this to illustrate that depending on the
value of the first argument, we may not even care about any of the rest.
sub foo {
my $type = shift;
if ($type == 'APIv3') {
carp "APIv3 unsupported\n";
return;
}
# perhaps do computationally intensive or transactional stuff here
# ..
my $arg1 = shift;
my $arg2 = 0;
if ($type == 'APIv2') {
$arg2 = shift;
}
return $arg1 + $arg2;
}
Granted, there's no performance benefit, but since certain variables
aren't introduced until after the conditional return case, it definitively
shows that those values aren't needed unless we pass the condition.
I think that using 'shift' as a little faucet that gives you stuff as you
need it is rather elegant.
--Jeremy
--
Jeremy Impson
Sr. Associate Network Engineer
Investigative Research & Marketing
Lockheed Martin Systems Integration
email: [EMAIL PROTECTED]
phone: 607-751-5618
fax: 607-751-6025
