-- Mike

--
just,my${.02}

# prototypes only check arg format
# i.e. (scalar/array/hash/code/glob and number of args)

package Sample;
sub stringify () {
    return ($_[0]->{data}) x $_[1]
}

package main;
sub print_string($) {
    print $_[0]->stringify(1)
}

my $obj = bless ( {data=>"foo\n"}, 'Sample');
print_string($obj); # fine
print_string(5);    # uh oh... basic numbers don't have a stringify me
+thod,
                    # yet the arg passed the prototype since 5 is a sc
+alar.
[download]

# methods don't check prototypes... at all.

sub print_string_bad($) {
print $_[0]->stringify() # Will pass the prototype, yet break since $_
+[1] will be 
                         # undef in stringify
}

print_string_bad($obj);
[download]

Hence the reason for the general distaste for prototypes among the perl community. For most cases, they're pointless. They're only there so that you can call your own subs like perl-builtins.

    sub foo ($$) {....}
    my @bar = (1, 2);
    foo @bar;
[download]

Abigail