[dojo-contributors] Improved mixin semantics

Scott J. Miles sjmiles at turboajax.com
Wed Aug 8 17:49:29 EDT 2007

Argh, I may have broken Dijit with this commit. Mea culpa. I'm on it.

Scott J. Miles
TurboAjax Group

Scott J. Miles wrote:
> In [10026] I've committed a refactored declare.js that has improved, 
> hopefully robust, mixin semantics.
> "inherited" should now work inside of mixin classes, and to travel into 
> and out of mixin trees.
> The basic syntax for inherited is like so:
> dojo.declare("bar", [base, mixin, mixin2], {
>    foo: function() {
>      this.inherited("foo", arguments);
>    }
> });
> Note that the first argument must be the name of the function and the 
> second argument must literally be 'arguments'. More on this below.
> The inherited call will seek ancestral 'foo' in right-to-left order. 
> Iow, first it looks in mixin2 (and up through it's ancestry) and then 
> into mixin, and finally base.
> I added a basic test in the test suite, hopefully you guys can bang on 
> it and see if there are any flaws (ahem, see where the flaws are). 
> Internally we've thrown some crazy structures at it and so far so good.
> Wrt to the signature, I realize that it's odd, but it makes the magic 
> happen.
> Note that in Dean's Base2 he's solved this problem by RegEx'ing method 
> code to detect the superclass call and then wrapping methods in closures 
> as needed to setup the necessary info. This is clever as usual and makes 
> most of the work into one-time preprocessing.
> The benefit of declare is that it works regardless of how a particular 
> method got into your class. That is, you can poke methods directly into 
> prototypes or instances and 'inherited' should still work properly.
> This was all a lot of work, so if you hate declare in general, or simply 
> would prefer some other tack, please start a new thread and give your 
> objective reasoning. I will be grateful as that will keep my head from 
> exploding. :)
> Regards,
> Scott J. Miles
> TurboAjax Group
> http://www.turboajax.com
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