[webkit-dev] JSObjectCallAsFunctionCallback question

[Xiong]

Hi, Su

Yes, this is the key point of the problem.

In my program, many Object use the same staticFunc entry[Program
Architecture].

So, in the getValue_cb callback function, we need do extra two things:

1.Get the Object name, here is "myObject"; [WE CAN NOW]
2.Get the propertyName of the method, here is "getValues"; [WE CAN NOT NOW]

After both get the Object and method's name, we can identify another
callback function.

Therefore, implement a way to get the propertyName of the method via
'function object' is needed.

Thanks.

-Xiong

On Fri, May 15, 2009 at 3:28 PM, Zhe Su <james.su at gmail.com> wrote:

> AFAIK, there is no way to achieve what you want by using staticFunc
> structure. Of course, if you use different C functions for each staticFunc
> entry, you actually don't need the name.
>
> Regards
> James Su
>
>
> On Fri, May 15, 2009 at 3:24 PM, Xiong <browserwk at gmail.com> wrote:
>
>> Thanks Su.
>>
>> I think i know you mean.
>>
>> To get the method name ["getValue"] via attach a private data to function
>> object which create by JSObjectMake().
>>
>> Yes, it's a better way, but not for me.
>>
>> In my program, we have many Object and it's method and now all in
>> staticFunc structure.
>>
>> Thanks again.
>>
>> -Xiong
>>
>>
>> On Fri, May 15, 2009 at 11:57 AM, Zhe Su <james.su at gmail.com> wrote:
>>
>>> If you create a JSObject with JSObjectMake() function, you can have a
>>> private data associated to the newly created JSObject. You can store
>>> anything you want in the private data. So following approach might be
>>> feasible for you:
>>>
>>> 1. define a special JSClass for your function, which has finalize and
>>> callAsFunction set. In finalize() method, you need destroy the private data
>>> associated to the JSObject, if necessary. callAsFunction points to your
>>> getValue_cb.
>>> 2. create the getValue function object by calling JSObjectMake() with the
>>> function name "getValue" as private data.
>>> 3. attach the function object to myObject with name "getValue". It might
>>> be done in myObject class's initialize() method.
>>> 4. in getValue_cb function you can retrieve the private data (which
>>> contains the name) by calling JSObjectGetPrivate(function).
>>>
>>> The only drawback of this approach: you can't declare the function
>>> statically in staticFunctions.
>>>
>>> Regards
>>> James Su
>>>
>>> On Fri, May 15, 2009 at 10:53 AM, Xiong <browserwk at gmail.com> wrote:
>>>
>>>> Thanks Darin.
>>>>
>>>> For the first problem, as you said, all the functions are objects, and
>>>> also have **properties**.
>>>>
>>>> So,can we add a member for the "function object" to store the method
>>>> name[here is "getValues"] in theoretical ?
>>>>
>>>> And this also like the "JSObjectRef object" variable in the callback
>>>> prototype,we can get the class name like this:
>>>>
>>>> toJS(object)->className().data()
>>>>
>>>> Thanks.
>>>>
>>>> -Xiong
>>>>
>>>>
>>>> On Fri, May 15, 2009 at 10:29 AM, Darin Adler <darin at apple.com> wrote:
>>>>
>>>>> On May 14, 2009, at 7:03 PM, Xiong wrote:
>>>>>
>>>>>  1    what is the purpose of the "JSObjectRef function" variable? In my
>>>>>> case, we never use.
>>>>>>
>>>>>
>>>>> It’s fine to not use this if you don’t need to. In JavaScript,
>>>>> functions are objects. Like other objects they can have properties. This
>>>>> argument is passed to your C implementation so that it can get access to
>>>>> properties of the function object if it has some reason to. In many cases
>>>>> there is no need to do this.
>>>>>
>>>>>  2    In this function, i want to get the propertyName of the method,
>>>>>> in this case, we need "getValues", can be implemented ?
>>>>>>
>>>>>
>>>>> No, there's no way to do that, for a good architectural reason.
>>>>>
>>>>> A JavaScript function is a first class object. Using JSObjectMake will
>>>>> create an object with a prototype that has functions stored in its
>>>>> properties, but there’s nothing to prevent the JavaScript program from
>>>>> taking that function and storing it somewhere else, in a property with
>>>>> another name. When the function is called, it’s just an object, and there’s
>>>>> no way to go back in time and find out where that object came from.
>>>>>
>>>>> Consider the similar situation of a data property. When you get the
>>>>> length of an array, it's a number 1, not a number 1 that knows it came from
>>>>> a property named "length".
>>>>>
>>>>>    -- Darin
>>>>>
>>>>>
>>>>
>>>> _______________________________________________
>>>> webkit-dev mailing list
>>>> webkit-dev at lists.webkit.org
>>>> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
>>>>
>>>>
>>>
>>
>
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