Want 0.14

Want is a Perl module created to implement the `want command.

SYNOPSIS

use Want;
sub foo :lvalue {
if (want(qwLVALUE ASSIGN)) {
print "We have been assigned ", want(ASSIGN);
lnoreturn;
}
elsif (want(LIST)) {
rreturn (1, 2, 3);
}
elsif (want(BOOL)) {
rreturn 0;
}
elsif (want(qwSCALAR !REF)) {
rreturn 23;
}
elsif (want(HASH)) {
rreturn { foo => 17, bar => 23 };
}
return
}

This module generalises the mechanism of the wantarray function, allowing a function to determine in some detail how its return value is going to be immediately used.

...

EXAMPLES

use Carp croak;
use Want howmany;
sub numbers {
my $count = howmany();
croak("Cant make an infinite list") if !defined($count);
return (1..$count);
}
my ($one, $two, $three) = numbers();


use Want want;
sub pi () {
if (want(ARRAY)) {
return [3, 1, 4, 1, 5, 9];
}
elsif (want(LIST)) {
return (3, 1, 4, 1, 5, 9);
}
else {
return 3;
}
}
print pi->[2]; # prints 4
print ((pi)[3]); # prints 1


sub backstr :lvalue {
if (want(qwLVALUE ASSIGN)) {
my ($a) = want(ASSIGN);
$_[0] = reverse $a;
return undef;
}
elsif (want(RVALUE)) {
my $t = scalar reverse $_[0];
}
else {
carp("Not in ASSIGN context");
}
return
}

print "foo -> ", backstr("foo"), "n"; # foo -> oof
backstr(my $robin) = "nibor";
print "$robin is now $robinn"; # $robin is now robin