Re: Object creation in SpiderMonkey 45

On Thursday, May 5, 2016 at 6:06:29 PM UTC+3, Boris Zbarsky wrote:
> On 5/5/16 8:56 AM, Mihai Dobrescu wrote:
> > but for some reason it doesn't call the custom toString when it is
> > created this way. Any hints?
> 
> Where does the custom toString live?  In your examples:
> 
> var ap1 = new AIRealPoint(3, 3);
> var r = new AIReal(3);
> 
> is it the case that Object.getPrototypeOf(r) ==
> Object.getPrototypeOf(ap1.h)?
> 
> Or put another way, when you say "h and v properties are defined using a 
> templated function, basically creating a custom object of type AIReal 
> (in this case) to return, using JS_NewObject", how _exactly_ are you 
> doing this?  What does the JS_NewObject callsite look like?
> 
> -Boris

I have a construction as follows:

const JSFunctionSpec jsAIReal::fFunctions[] = {
    JS_FN("toString", jsAIReal::ToString, 0, JSPROP_PERMANENT | JSPROP_ENUMERATE),
    ...

    JS_FS_END
}

passed to JS_InitClass (in a template class...):

static void DefineClass(JSContext *cx, JS::Handle<JSObject*> global)
    {
        try
        {

jsType::fProtoObj = JS_InitClass(cx, global,
                nullptr, &fClass,
                Constructor, jsType::fConstructorNumberOfArguments,
                jsType::fProperties, jsType::fFunctions, jsType::fStaticProperties, jsType::fStaticFunctions);

            if (!jsType::fProtoObj)
            {
                throw new jsEngineException("jsEngine error at definiton of %s.", fClass.name);
            }
}
        catch (...)
        {
            throw new jsEngineException("jsEngine error at definiton of %s.", fClass.name);
        }
    }

A property getter looks like:

template<typename jsType, typename jsPropertyType, typename jsPropertyType::PrivateType PrivateType::*Property>
    static bool GetProperty(JSContext *cx, unsigned argc, JS::Value *vp)
    {
        JS::CallArgs args = CallArgsFromVp(argc, vp);

        PrivateType* data = (PrivateType*)(JS_GetPrivate(&args.thisv().toObject()));

        if (!data)
            return false; // +throw error...

        JSObject *obj = JS_NewObject(cx, &jsDataClass<jsPropertyType>::fClass);

        JS_SetPrivate(obj, new jsPropertyType::PrivateType(data->*Property));

        args.rval().setObject(*obj);

        return true;
    }

used as follows:

const JSPropertySpec jsAIRealPoint::fProperties[] = {
	CLASS_JS_PSGS_PROPERTY(jsAIRealPoint, jsAIReal, h),
	CLASS_JS_PSGS_PROPERTY(jsAIRealPoint, jsAIReal, v),

    JS_PS_END
};

where I have:

#define CLASS_JS_PSGS_PROPERTY(JS_TYPE, JS_PROPERTY_TYPE, PROPERTY) \
JS_PSGS(#PROPERTY, (JS_TYPE::GetProperty<JS_TYPE, JS_PROPERTY_TYPE, &JS_TYPE::PrivateType::PROPERTY>), \
                   (JS_TYPE::SetProperty<JS_TYPE, JS_PROPERTY_TYPE, &JS_TYPE::PrivateType::PROPERTY>), JSPROP_PERMANENT | JSPROP_ENUMERATE)

A bit hard to read this...sorry.

Note, it worked fine in 38.