in reply to Re^7: Introducing Class::InsideOut
in thread Introducing Class::InsideOut

It will work as long as the @ISA gets set up correctly. It's no different than what Class::InsideOut does to support inside-out objects. All anno's solution does is provide a default constructor that can take a foreign object.

Ah. Quite right. If you setup ISA appropriately it will still work. Still reblessing an already initialised object seems far more evil than the coupling of creation/initialisation it's trying to avoid. Not something I'd expect if I was reading the code.

Not that I disagree with the general concept - but I think C::IO made the right decision in not providing a default constructor. It makes it much easier to apply it to pre-existing class hierarchies no matter how they're organised.

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Re^9: Introducing Class::InsideOut
by Anno (Deacon) on Feb 17, 2006 at 12:15 UTC

    Ah. Quite right. If you setup ISA appropriately it will still work. Still reblessing an already initialised object seems far more evil than the coupling of creation/initialisation it's trying to avoid. Not something I'd expect if I was reading the code.

    If you want to inherit from a foreign class in this particular way (substituting the foreign object for the standard undefined scalar), reblessing must be expected. Apart from esthetic objections I don't see a big problem with that.

    Anno

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      If you want to inherit from a foreign class in this particular way (substituting the foreign object for the standard undefined scalar), reblessing must be expected.

      Erm... it's perfectly possible to inherit from another class without reblessing. It's one of the major advantages of the inside-out approach. For example:

      {   package MySubClass;
    use base qw( SomeHashBasedClass );
    use Class::InsideOut qw(:std);
    
    sub new {
        my $class = shift;
        my $self = $class->SUPER::new( @_ );
        return register( $self );
    }
};

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        You are right, thanks for pointing it out. You have the general problem that SUPER isn't guaranteed to pick up the right class with multiple inheritance.

        While I don't see reblessing as evil, (what is the big problem?) I avoid it where possible. It's ugly and looks like you can't make up your mind. I guess I could come up with an alternative universal ->new that doesn't re-bless foreign objects, but that's the problem with this discussion.

        We're comparing the solid Class::InsideOut with some not-yet-written counter-example of mine. I can wriggle out of any argument by redefining the example. For the moment, if you don't mind, I'd rather give it a rest until there is something more concrete to discuss. It's been instructive so far.

        Anno

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