Re: Relaxing SVGList* item object equality in Blink/Chromium

On Thu, Dec 12, 2013 at 2:58 PM, Kouhei Ueno <kouhei@google.com> wrote:

> 2013/12/12 Robert O'Callahan <robert@ocallahan.org>:
> > For example, does this mean svgElement.x !== svgElement.x? Or
> > svgElement.x.baseVal != svgElement.x.baseVal?
>
> I want to drop guarantees about svgElement.x === svgElement.x, and
> svgElement.x.baseVal === svgElement.x.baseVal. They may ===, but it
> may not be all the time.
>

That's bad. A basic principle of Web APIs is that DOM attribute getters
consistently return the same object unless the author does something to
explicitly change them. See
http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2013-November/041333.htmland
the rest of that thread.

I think instead of just saying you'll violate the spec in some
not-very-well-defined ways, you really should propose a spec change that
puts the spec into a state Blink will comply with. That will help everyone
understand the impact of what you're proposing to do.

We did a lot of work in Gecko a few years ago so we could comply with the
spec without creating the implementation issues discussed in the blink-dev
thread, and I think we did a pretty good job since we haven't had those
issues since. So it is possible.

Rob
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