I like Bart's Re: It's one of the reasons I wrote vars::i idea for an isa.pm so much, that I worked a bit more on it. The only thing I have against it, is that you would need to say "use isa qw(Bar)". It should be possible to do this shorter. Something like: 
require isa; # this should go away once this is in the core
package Foo;
isa Bar;

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I came up with the following (temporary) implementation: 
package isa;
use strict;
use warnings;

BEGIN {
    no warnings 'redefine';
    my $old = \&UNIVERSAL::isa;
    *UNIVERSAL::isa = sub {
        goto &$old if defined wantarray;
        no strict 'refs';
        push @{caller().'::ISA'}, @_;
    } #UNIVERSAL::isa
}
1;

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The code depends on giving another meaning of the UNIVERSAL::isa subroutine, namely when it is being called in void context: in that case it will set the caller's @ISA array with the parameters passed.

I like the syntax this gives. It has its limitations though, as you can list only one inheritance at a time. That's because the syntax of: 

isa Bar;

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actually is the indirect object syntax for: 
Bar->isa;

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I wonder what other Monks think of this: is it a good idea? or is it an abomination? To me, it is one of the first "natural" uses of indirect object syntax.

Liz

In reply to package Foo; isa Bar; why not? by liz

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