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Ovid (2709)
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Stuff with the Perl Foundation. A couple of patches in the Perl core. A few CPAN modules. That about sums it up.
Prototype OO and Multiple Inheritance?
I'm thinking about the my Roles talk at YAPC::EU::2009, (you know the conference, right? The one I made that strange little promo for?). It's a bit of a tutorial, but not much. It's more about the "why" instead of the "how" because even though I get plenty of comments/emails about roles, they're almost always in the "why" category. That's because roles are so easy to use once you start that you really need motivation for starting rather than a guide on how to start (though I'll give some of that, too).
One thing I am doing is a bit of comparing/contrasting with multiple languages and how they all struggle to figure out how to manage inheritance. Everyone seems to have a different idea, but I'm stumped on Javascript and other prototyped OO languages.
Prototyped OO languages don't have classes. Thus, you really can't inherit. However, you use an existing object as a "prototype", clone it, and then add state/behaviors as needed. So one might think there's a loose analogy to inheritance there. What I'm wondering is whether or not this enforces a tree-like hierarchy on object systems? Is there any analogue to multiple inheritance? If not, how is this worked around. Every language I've ever used which forbids MI has a workaround (interfaces, mixins or the weird stuff that BETA does). Any other comments about prototype OO languages welcome (particularly if you have experience with examples other than JavaScript).
I pour myself a cup of strong coffee. :-)
-- Jarkko Hietaniemi
JSAN modules implement inheritance (Score:1)
Take a look through some of the JSAN stuff. There was a bunch of work that got done on implementing what I believe we were calling pseudo-classes.
http://openjsan.org/doc/r/rk/rkinyon/Class/0.05/lib/Class.html [openjsan.org]
http://openjsan.org/doc/l/ly/lyokato/Class/Setup/0.04/lib/Class/Setup.html [openjsan.org]
http://openjsan.org/doc/i/in/ingy/Subclass/0.10/lib/Subclass.html [openjsan.org]
Self and NewtonScript (Score:1)
If memory serves, Self had a system to make any slot a parent-slot - by convention "parent*" was the object cloned from, but any slot could be a parent-slot by adding a * to the name. How dispatch was eventually (mis-)handled, I have no recollection...
NewtonScript was based on Self, but extended the convention to always have two parent-slots for gui-elements (business-object + gui-object), but not any more, as I recall.
And speaking of prototype-based language, why would anyone add first-order functions
Re: (Score:1)
Huh? JavaScript has closures. They work perfectly well. I've been using them for years.
But there is a major gotcha. Variables declared with var are always scoped to the nearest function call. So if you create closures in a loop, they will all point to the same variable. However once you know that's the issue, that's easily fixed - just call a function from within the loop whose job is to scope the variable correctly.
Re: (Score:1)
I always thought of Prototype OO ... (Score:1)
as "Every Class is a Singleton and is Instantiated", which glosses over a bunch of stuff but does roughly fit the way things like Joose [google.com] are dealing with JS's Prototype OO.
A paper and a post (Score:1)
Also Steve Yegge's Universal Design Pattern [blogspot.com] (aka Propertise Pattern) covers the topic quite thoroughly.
broquaint out
Re: (Score:2)
Nope, not old news at all. Thanks for the tip!