use Perl

• no gnosis; (Score:2)

  by Simon (89)

  According to that diagram, ::Point is not a ::Class. Can that be right?
  • Re:no gnosis; (Score:2)

    by autrijus (1505)

    A Point is-a Object... That is, ::Point inherits from its superclass, ::Object, as shown by the white pizza-arrow line. Surely a Point object would not be a valid class object.

    On the other hand, the metaclass object ::Point itself -- on the left-hand side -- is an instance of ::Class, as shown by the dotted line.
    • Class versus metaclass (Score:2)

      by Simon (89)

      I think I see what you mean but I don't like the class/metaclass distinction at all. I'm in favour of pulling everything out into the runtime side of the drawing. That is, I think ::Point and ::Point.meta should be the same, and ::Point is not just a metaclass object but an honest-to-goodness class object. Why the distinction?
      • Re:Class versus metaclass (Score:2)

        by autrijus (1505) on 2005.08.14 5:45 (#42606) Homepage Journal

        The idea is the left-hand-side MetaClass should not be distinguishable, by the user, from the right-hand-side ::Class.

        Conceptually, if we are implementing perl6 on perl6, then sure ::Class is just the metaclass itself.

        But if you are, say, implementing perl6 on perl5 (which is what we're doing now), then you need a perl5-side entity to represent a perl6 class. That's what the MetaClass is.

        Otherwise, you can't communicate with other perl5 objects -- "native" ones like DBI.

        But it is that exact entity that gets exposed as a ::Class object, so the user won't be able to tell the difference.

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