[webkit-dev] why js script" var a = new XMLHttpRequest; ", it's ok; but "var a = new StyleSheet; ", it'll throw an exception?

[Suk Zhong]

Hi dave:
        Thanks your response.running the following script "var a = new
CSSStyleSheet;" will also throw an exception like  "var a = new
StyleSheet;".

Best Regards
Suk

2009/6/5 David Hyatt <hyatt at apple.com>

> Just a guess, but I believe StyleSheet is abstract, and if you want to
> craft a stylesheet, you'd probably use CSSStyleSheet instead.
>
> dave
>
>
> On Jun 5, 2009, at 3:28 AM, Suk Zhong wrote:
>
>  Hi All:
>>   We're trying to extend WebKit dom js binding.We have some questions.
>>
>>   in DOMWindow.idl having the following code:
>>   attribute StyleSheetConstructor StyleSheet;
>>   attribute [JSCCustomGetter] XMLHttpRequestConstructor XMLHttpRequest;
>>
>>   and we find class JSXMLHttpRequestConstructor has function
>> getConstructData, while JSStyleSheetConstructor doesn't have function
>> getConstructData.
>>
>>   if test the following js script:"var a = new XMLHttpRequest;", it's
>> ok;but "var a = new StyleSheet;", it'll throw an exception.
>>
>>   and we trac this problem to Interpreter::privateExecute() and
>> JSValuePtr::getConstructData function
>>
>>   inline ConstructType JSValuePtr::getConstructData(ConstructData&
>> constructData)
>>   {
>>        return JSImmediate::isImmediate(asValue()) ? ConstructTypeNone :
>> asCell()->getConstructData(constructData);
>>   }
>>   and we know this function returns ConstructTypeNone for
>> JSStyleSheetConstructor object,  ConstructTypeHost for
>> JSXMLHttpRequestConstructor object;
>>
>>   JSStyleSheetConstructor object and JSXMLHttpRequestConstructor object
>> are returned by the same template function getDOMConstructor.
>>
>>   our questions are:
>>
>>   1.why it has this return?
>>   2.which codes make the two object have different immediate value?
>>   3.some people can explain the whole role of class JSImmediate?
>>   4.our trac maybe be not correct,who can explain why newing StyleSheet
>> has exception and newing XMLHttpRequest is OK?
>>
>> Thanks and Best Regards
>>
>> Suk
>> _______________________________________________
>> webkit-dev mailing list
>> webkit-dev at lists.webkit.org
>> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
>>
>
>
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