Re: WebIDL and prototype chains

On Jul 16, 2009, at 10:45 AM, Adam Barth wrote:

> When a browser creates an instance of a DOM object defined by an
> WebIDL interface, the browser must choose where to connect it's
> prototype chain.  For example, consider this case (where frames[0] is
> a same-origin child frame):
>
> var doc = frames[0].document;
>
> 1) To which global object's prototypes ought |doc| connect to, the
> parent frame running the script or the child frame from which we
> obtained the document?
>
> 2) Where is this behavior specified?  If the behavior is currently not
> specified, which spec ought to contain the requirements?
>
> My best guess is that the prototype chain ought to connect to the
> child's prototype (because the document "is owned by" the child frame)
> and that the WebIDL spec ought to include this requirement (because
> WebIDL explains how to reify abstract DOM interfaces in ECMAScript).
>
> Thoughts?

One thing to note: any object or method that is exposed cross-origin  
should specifically *not* have this behavior. Instead, it should  
create a separate interface object in every frame that accesses the  
property. window.history, window.location and window.postMessage are  
examples that require this treatment. Web IDL needs to give a hook to  
other specs so they can specify that cross-origin properties need to  
get this different treatment.

Regards,
Maciej