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

From: Kouhei Ueno <kouhei@google.com>
Date: Thu, 12 Dec 2013 12:45:05 +0900
Message-ID: <CAPVAxLU7TrruGw03wtfWtM0THBCSqOMF4NwaahRef6h9aJwRfA@mail.gmail.com>
To: "Robert O'Callahan" <robert@ocallahan.org>
Cc: www-svg <www-svg@w3.org>
Thanks for your feedback!

For DOM attribute getters, I will explore alternative implementation
designs so I can keep it consistent, guaranteeing svgElement.x ===
svgElement.x, and
svgElement.x.baseVal === svgElement.x.baseVal.

What do you think about list item getters? They are methods, not attributes.
Would your opinion be different for "list.getItem(0) !== list.getItem(0)"?

2013/12/12 Robert O'Callahan <robert@ocallahan.org>:
> 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.html
> and 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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Kouhei Ueno
Received on Thursday, 12 December 2013 08:20:19 UTC

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