[webkit-dev] js binding: function argument type checking

[Mo, Zhenyao]

Hardly.  Right now we already do the type checking in the generated
toType(argument) functions.  Instead of casting to null, we throw a
TypeError, which adds no extra cost if the type is correct.

Besides, where I looked, after toType(argument) call, exception is
checked.  Only that currently toType(argument) is not generating
exceptions.

Mo

On Thu, Aug 12, 2010 at 9:20 AM, Sam Weinig <sam.weinig at gmail.com> wrote:
>
>
> On Wed, Aug 11, 2010 at 10:58 PM, Darin Fisher <darin at chromium.org> wrote:
>>
>> On Wed, Aug 11, 2010 at 10:37 PM, Sam Weinig <sam.weinig at gmail.com> wrote:
>>>
>>> On Wed, Aug 11, 2010 at 10:29 PM, Cedric Vivier <cedricv at neonux.com>
>>> wrote:
>>>>
>>>> On Thu, Aug 12, 2010 at 13:26, Sam Weinig <sam.weinig at gmail.com> wrote:
>>>>>
>>>>> For this specific case, it seems like you could easily check for a null
>>>>> WebGLProgram* in WebGLRenderingContext::useProgram and set the
>>>>> ExceptionCode.
>>>>
>>>> Nope, null is a valid argument, it bounds to the initial program, which
>>>> means nothing will be drawn with WebGL.
>>>> Certainly not the expected behavior when one pass the wrong type to the
>>>> argument like Zhenyao pointed out, therefore throwing TypeError really makes
>>>> sense here (and elsewhere with WebGL API).
>>>
>>> Ok, in that case, it seems like you need to do it in the bindings for
>>> this. I would prefer not making a sweeping change at this time, and instead
>>> keeping the changes just to places where the extra checking is necessary due
>>> to ambiguity (as in this useProgram case).
>>> -Sam
>>
>> Out of curiosity, if we have the ability for code to be auto generated
>> from the IDL, why not use it universally?  I'm trying to guess to understand
>> your preference :)
>> -Darin
>
> My concern with doing it universally is the performance cost of doing the
> check twice in many places (once in the bindings and once in the
> implementation with a null check). We could certainly re-evaluate the way we
> do these type checks, potentially even converting the existing null checks
> in the implementation to asserts, but I think that discussion shouldn't be
> conflated with this bug fix.
> -Sam
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