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Re: [Selectors API 2] Is matchesSelector stable enough to unprefix in implementations?

From: William Edney <bedney@technicalpursuit.com>
Date: Fri, 25 Nov 2011 09:49:08 -0600
Cc: Lachlan Hunt <lachlan.hunt@lachy.id.au>, Boris Zbarsky <bzbarsky@MIT.EDU>, public-webapps@w3.org
Message-Id: <DAEE46F6-F338-4103-9AB4-46D0F79C1F99@technicalpursuit.com>
To: Sean Hogan <shogun70@westnet.com.au>
All -

I'm going to throw my 2 cents in here and say that, whatever ends up happening with scoping, that the equivalent of the current querySelector()/querySelectorAll() should be named matchesSelector().

As a longtime Web developer (and trainer of other Web developers) it is important to me to have consistency in naming above all else. JS libraries can always alias / wrap these names should they so desire. Name shortening has already been occurring... if we had followed 'old W3C DOM-style naming', querySelectorAll() would've been 'documentGetElementsBySelector()'.

Providing a balance between short names and descriptive names is important. One of the things that drives me nuts about the (non-standard) 'document.evaluate()' call (exists on FF / Webkit to query using XPath), is that it is not explicit enough... 'evaluate' what? JS? XPath? CSS?

While I don't disagree that shorter names could've been chosen all of those years ago, as Austin Powers would say, "That train has sailed, baby..."

Cheers,

- BIll

On Nov 25, 2011, at 8:04 AM, Sean Hogan wrote:

> On 25/11/11 6:49 PM, Lachlan Hunt wrote:
>> On 2011-11-25 01:07, Sean Hogan wrote:
>>> On 24/11/11 7:46 PM, Lachlan Hunt wrote:
>>>> On 2011-11-23 23:38, Sean Hogan wrote:
>>>>> - If you want to use selectors with :scope implied at the start of each
>>>>> selector in the selector list (as most js libs currently do) then you
>>>>> use find / findAll / matches.
>>>> 
>>>> The matches method will not change behaviour depending on whether or
>>>> not there is an explicit :scope because it is always evaluated in the
>>>> context of the entire tree. There is never an implied :scope inserted
>>>> into the selector, so there will not be two alternative matches methods.
>>> 
>>> If and when there is a need for a matching method that does imply :scope
>>> (which I provided a use-case for in
>>> http://lists.w3.org/Archives/Public/public-webapps/2011OctDec/0342.html)
>>> then it could be called matches().
>> 
>> Oh, it wasn't clear that you were talking about a case involving explicit reference nodes before.
>> 
>> But adding two separate methods that are only subtly different would add more complexity for authors, since the difference will not always be obvious where there is no explicit reference nodes supplied and they may get them confused.
>> 
>> In fact, with a method that always prepends :scope, it could result in an unexpected result in some cases:
>> 
>> e.g.
>> 
>>   root.matches("html.foo");
>>   root.matchesSelector("html.foo");
>> 
>> These aren't obviously different, but when you consider that the first would always prepend :scope under your proposal, the first would unexpectedly return false, since it's equivalent to:
>> 
>>   root.matchesSelector(":scope html.foo");
>> 
>> This would happen whether the root element is the root of the document, or the root of a disconnected tree.
>> 
>> We could instead address your use case by implying :scope if a refElement or refNodes is supplied.  That way, if the author calls .matches() without any refNodes, they get the expected result with no implied :scope.  If they do supply refNodes, and there is no explicit :scope, then imply :scope at the beginning.
>> 
>> This approach would be completely backwards compatible with the existing implementations, as nothing changes until refNodes/refElement and :scope are supported.
>> 
> 
> You mentioned this before, but anyway:
> 
> el.matches("div span") -> ok
> 
> el.matches("> div span") -> throws, because no :scope implied
> 
> el.matches("div :scope span") -> ok, but can't match anything
> el.matches("> div span", refNode) -> ok
> el.matches("div :scope span", refNode) -> ok
> 
> el.matches("div span", refNode) -> what does this do? How do you know that the intention isn't to just ignore the refNode if there is no explicit :scope?
> 
> I guess if you wanted this last behavior, you could call something like
>    /:scope\b/.test(selector)
> before-hand and if it is false then not pass the refNode to matches().
> 
> I'm not sure if there are other problematic cases.
> 
> Sean
> 
> 
Received on Friday, 25 November 2011 15:49:38 GMT

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