W3C home > Mailing lists > Public > www-svg@w3.org > July 2009

Re: Canvas and Interactivity

From: Cameron McCormack <cam@mcc.id.au>
Date: Fri, 24 Jul 2009 10:08:48 +1000
To: Jonathan Watt <jwatt@jwatt.org>
Cc: Robert O'Callahan <robert@ocallahan.org>, Jeff Schiller <codedread@gmail.com>, anthony.grasso@cisra.canon.com.au, www-svg <www-svg@w3.org>
Message-ID: <20090724000848.GA1287@arc.mcc.id.au>
Cameron McCormack:
> > A valueOf method on an object allows it to be converted into a primitive
> > when used with particular operators:

Jonathan Watt:
> Wouldn't it always be the case, not just for particular operators? If not, when
> would rect.x evaluate to a Number, and when would it evaluate to an
> SVGAnimatedLength?

In particular, unary ! won’t invoke valueOf on the object.  It just
evaluates to true for any object.

Even more troublesome would be == and !=.  If you had rect.x and rect.y
both be SVGAnimatedLengths whose values were 10, then rect.x == rect.y
will evaluate to false, since == will check for object identity.  You’d
need to do rect.x == +rect.y or something instead.

I’m beginning to think that there are too many exceptions and that this
will confuse authors.

-- 
Cameron McCormack ≝ http://mcc.id.au/
Received on Friday, 24 July 2009 00:09:51 GMT

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