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Re: [WebIDL] On overloaded operations in an effective overload set

From: Cameron McCormack <cam@mcc.id.au>
Date: Mon, 2 Mar 2009 10:45:54 +1100
To: public-webapps@w3.org
Message-ID: <20090301234554.GA7585@arc.mcc.id.au>
Hi Shiki.

Shiki Okasaka:
> I have a question about the overloaded operations in an effective
> overload set in Web IDL.  In the example of 'Interface A' in 3.3.3.
> Operation, the Draft 19 December 2008 says,
> 
>     "There are thus no overloaded operation resolution ambiguities for
> the interface",
> 
> but the following three pairs seem to be not distinguishable to me,
> 
>  * <f2, (DOMString, DOMString)> and <f3, (long, DOMString)>
>  * <f2, (DOMString, DOMString, float)> and <f3, (long, DOMString, DOMString)>
>  * <f2, (DOMString, DOMString, float, float)> and <f3, (long,
> DOMString, DOMString, float)>
> 
> based on the definition of 'distinguishable':
> 
>     "Two types, t and u, are distinguishable if both are objects
> implementing an interface (where two different interfaces are
> identified) or if one is an object implementing an interface and the
> other is a primitive type."
> 
> Since 'DOMString', 'long', and 'float' are primitive types, there is
> no index i such that the types at index i are distinguishable in the
> above pairs.

Yes, you are correct.  I think it would be helpful to allow DOMString
and the other primitive types to be distinguishable, as the example
would need.

I’ve added a note to the editor’s draft to fix this up at some point.

Do you have an opinion on how disambiguation should be performed for an
ECMAScript value passed in to such an overloaded operation?

> We are currently developing a Web IDL based RPC system for Native
> Client (*) to facilitate defining interfaces between JavaScript and
> Native Client based safe x86 modules, and a little clarification about
> this section will help us with our Web IDL compiler development.

Interesting to see a use of Web IDL other than in a W3C specification!

> Also I found two typos in the draft:
> 
> 3.8.13. [Variadic]
> interface IntegerSet {
>  readonly unsigned long cardinality; # 'attribute' is missing after 'readonly'
> 
>  void union([Variadic] in long ints);
>  void intersection([Variadic] in long ints);
> };
> 
> 4.2.5. [Replaceable]
> interface Counter {
>  [Replaceable] readonly attribute unsigned value;  # 'long' or 'short'
> is missing after 'unsigned'
>  void increment();
> };

Fixed, thanks.

Cameron

-- 
Cameron McCormack ≝ http://mcc.id.au/
Received on Sunday, 1 March 2009 23:46:45 GMT

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