- From: Cameron McCormack <cam@mcc.id.au>
- Date: Wed, 15 Jul 2009 18:55:37 +1000
- To: Robert O'Callahan <robert@ocallahan.org>
- Cc: Jeff Schiller <codedread@gmail.com>, anthony.grasso@cisra.canon.com.au, www-svg <www-svg@w3.org>
Robert O’Callahan:
> What does that mean for those of us who fear WebIDL?
:)
A valueOf method on an object allows it to be converted into a primitive
when used with particular operators:
>>> rect = { x: { valueOf: function() { return 12.5 } } }
[object Object]
>>> rect.x + 50
62.5
The internal [[DefaultValue]] method by default in ES232 calls valueOf
on the object. So another way to achieve the same effect (the
SVGAnimatedLength object acting like a Number in some contexts) would be
to override that [[DefaultValue]].
http://bclary.com/2004/11/07/#a-8.6.2.6
It’s not perfect, though. And it feels a bit too “clever”. It also
wouldn’t work for SVGAnimatedBoolean objects, since the ECMAScript
ToBoolean() operator doesn’t invoke [[DefaultValue]] like ToNumber()
does.
If we could get away with it, I agree that it would be better to just
replace the SVGAnimated* things with something simpler like what you
suggest.
--
Cameron McCormack ≝ http://mcc.id.au/
Received on Wednesday, 15 July 2009 08:56:33 UTC