Re: Re: AUTOLOAD does not scale

[rir]

Agreed, but I say playing nicely is a practice that does not scale. If you won't distribute the code there is nothing wrong with using AUTOLOAD.

I am saying that AUTOLOAD does not scale well. Every use of AUTOLOAD in a program should be under the control of one party. If two separate authors use AUTOLOAD in the same program breakage is likely.

Being conservative, I would be suspicious of any program with more than one AUTOLOAD. If two AUTOLOAD routines exist in a hierarchy there is a problem. (Don't forget UNIVERSAL.)

This is a known problem. Consider:

#!/usr/bin/perl
use strict;
use warnings;

# I decide to use a module
package Vehicle;
use vars '$AUTOLOAD';

sub new { return bless {}, $_[0]; }

# handle all "V*" calls
sub AUTOLOAD {
        my ($key) =  $AUTOLOAD =~/::(\w+)/;
        return if $key =~ /^[A-Z]+$/;
        die "Vehicle::AUTOLOAD can't cope as $key"
                unless $key =~ /^[vV]/;
        print "Leaving  Vehicle::AUTOLOAD as $key$/";
}


# with my program below

package Animal;
use vars '$AUTOLOAD';

sub new { return bless {}, $_[0]; }

# handle all "A*" calls
sub AUTOLOAD {
        my ($key) =  $AUTOLOAD =~/::(\w+)/;
        return if $key =~ /^[A-Z]+$/;
        die "Animal::AUTOLOAD can't cope as $key"
                unless $key =~ /^[aA]/;
        print "Leaving  Animal::AUTOLOAD as $key$/";
}


package Horse;
use vars qw/ @ISA /;
@ISA = qw/ Vehicle  Animal /;



package  main;

# the two usages cannot work together,  I needed to
# know that Vehicle used AUTOLOAD so I could avoid it
# or rewrite my code to eliminate AUTOLOAD.

my $h = Horse->new;
$h->Veh();
$h->Ani();  # call intercepted by Vehicle AUTOLOAD

Be well.