Re: Upgrading from Spidermonkey 1.8.5 to 45. How to get property name in getters/setters now they are JSNatives and tiny IDs have been removed?

Hi Miles,

so far I know, you have define different property getter/setter for each
property. That's the way I did it.

Thomas


Am 05.06.2017 um 11:31 schrieb Miles:
> Hi,
> 
> I'm trying to upgrade my embedding from 1.8.5 to 45 and one of the things that I'm struggling with is how property getters/setters now work in 45.
> 
> In 1.8.5 I used tiny IDs and JSPropertySpec to define properties and getters/setters for a class.
> e.g. In 1.8.5 I had something like
> 
> enum part_tinyid {
>     PART_HEADING,
>     PART_PID,
>     PART_SECID,
>     PART_MID,
>     ...
> };
> 
> JSPropertySpec dj_Part_dynamic_props[] =
> {
>     {"heading", PART_HEADING,  flags,  dj_get_part_prop, dj_set_part_prop },
>     {"pid",     PART_PID,      flags,  dj_get_part_prop, dj_set_part_prop },
>     {"secid",   PART_SECID,    flags,  dj_get_part_prop, dj_set_part_prop },
>     {"mid",     PART_MID,      flags,  dj_get_part_prop, dj_set_part_prop },
> ...
>     { 0 }
> };   
> 
> 
> and then my getter was something like
> 
> JSBool dj_get_part_prop(JSContext *cx, JSObject *obj, jsid propid, jsval *vp)
> {
>     jsval id = JS_IdToValue(cx, propid, &id);
>     int idint = JSVAL_TO_INT(id);
> 
>     switch (idint)
>     {
>         case PART_HEADING:
>             ...
>             break;
> 
>         case PART_PID:
>             ...
>             break;
>     }
> 
> }
> 
> i.e. I had a single getter and a single setter for all of the properties and I could find which property I was getting/setting from propid
> 
> Now in Spidermonkey 45 Tiny IDs have been removed and dj_get_part_prop/dj_set_part_prop are JSNatives so I have something like:
> 
> JSPropertySpec dj_Part_dynamic_props[] =
> {
>     JS_PSGS("heading", dj_get_part_prop, dj_set_part_prop, flags),
>     JS_PSGS("pid",     dj_get_part_prop, dj_set_part_prop, flags),
>     JS_PSGS("secid",   dj_get_part_prop, dj_set_part_prop, flags),
>     JS_PSGS("mid",     dj_get_part_prop, dj_set_part_prop, flags),
> ...
>     JS_PS_END
> }; 
> 
> 
> JSBool dj_get_part_prop(JSContext *cx, unsigned int argc, JS::Value *vp)
> {
>     JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
>     JS::RootedObject obj(cx, JS_THIS_OBJECT(cx, vp));
> }
> 
> I can get the object by using JS_THIS_OBJECT and I can see that in the getter argc is 0, in the setter argc is 1 and args[0] contains the value of the property to set.
> However, I can't see any way to find out *which* property I am getting/setting.
> 
> Am I being stupid here? How can I find out which property I am getting/setting? I know that tiny IDs have gone so I was expecting the property to be passed as a string or something.
> Or is there no way of getting the property name and I have to use a different property getter/setter for each property?
> 
> If someone can help me I would be very grateful.
> 
> Thanks
> 
> Miles
> _______________________________________________
> dev-tech-js-engine mailing list
> [email protected]
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> 

-- 
Dipl.-Ing. Thomas Richter

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