[webkit-dev] About WebIDL supplemental interfaces

Andrei Bucur abucur at adobe.com
Thu Jul 19 09:29:01 PDT 2012

Hey Kentaro,

On 7/19/12 6:20 PM, "Kentaro Hara" <haraken at chromium.org> wrote:

>Hi Andrei
>> I'm asking this because CSS Regions spec defines the Region interface
>>as an
>> WebIDL supplemental interface that needs to be implemented by any object
>> that can be a region (Element, Pseudo elements etc.). Is there a way in
>> WebKit to write an interface that "implements" another as specified by
>> WebIDL?
>Currently, no. (Correct me if I'm wrong.)
>> However, WebKitIDL defines "Supplemental" more like a "partial
>> http://trac.webkit.org/wiki/WebKitIDL#Supplemental
>The current WebKitIDL implementation is "on the way". Eventually we
>want to remove the [Supplemental] IDL attribute and support the "A
>implements B" syntax as defined in the WebIDL.
>Do you have any alternative solution to make CSS Regions work without
>the "A implements B" syntax? If no, maybe it's time to consider
>supporting the "A implements B" syntax (, which would require a
>substantial amount of work though:-).

The only way I can see this implemented without the new syntax is by
writing some crazy hacks, probably very similar with how EventTarget
works. And even then I'm not sure everything will work out well. Right
now, hacking things in does not seem to worth the effort, especially if
it's going to be removed once the "implements" syntax gets in. I'm open to
suggestions though :).
However, it would be nice to have the new syntax on board sooner than
later. Is there a roadmap for adding this in WebKit? I'm sure you are very
busy so having a timeline would allow other hackers help move the
implementation forward :).


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