Hello James, TL;DR;: the SetAccessor() Api creates data properties that behave differently than expected by JavaScript spec, see https://crbug.com/336325111 for details.
Indeed, if your code is relying on triggering a setter callback installed on the prototype object then the SetNativeDataProperty() does not fit your needs. The right way to go would be to use SetAccessorProperty() Api that'll define a proper accessor property in JavaScript sense and for such a property an attempt to store via a child object would trigger the setter callback. While we are on the V8 Api changing topic, here's another cleanup project we are working on which might theoretically affect your code: https://crbug.com/333672197. Regards, -- Igor On Sun, May 19, 2024 at 10:14 PM 'James Snell' via v8-dev < v8-dev@googlegroups.com> wrote: > In Cloudflare Workers we just updated to v8 12.6 and spotted a new pending > deprecation notice saying to move from using SetAccessor to > SetNativeDataProperty. Unfortunately, there appears to possibly to be an > issue with that when using a `v8::FunctionTemplate` and setting the > accessor property on the `PrototypeTemplate()` > > Take for example the following snippet (there are a few utility methods in > here from the workerd codebase like check() and `js.str(...)` etc that are > just helpers... > > auto tmpl = v8::FunctionTemplate::New(js.v8Isolate, nullptr); > v8::Local<v8::String> foo = js.str("foo"_kj); > > tmpl->PrototypeTemplate()->SetNativeDataProperty(foo, > [](v8::Local<v8::Name> name, const > v8::PropertyCallbackInfo<v8::Value>& info) { > auto& js = Lock::from(info.GetIsolate()); > > info.GetReturnValue().Set(v8::Local<v8::Value>(js.str("foo"_kj))); > }, > [](v8::Local<v8::Name> name, v8::Local<v8::Value> value, > const v8::PropertyCallbackInfo<void>& info) { > KJ_DBG("Setter is called!"); > info.GetReturnValue().Set(value); > }, v8::Local<v8::Value>(), v8::PropertyAttribute::None); > > v8::Local<v8::Object> obj = > check(tmpl->InstanceTemplate()->NewInstance(js.v8Context())); > > // The setter is not called in this case! > check(obj->Set(js.v8Context(), foo, js.num(1))); > > // The setter IS called in this one > check(obj->GetPrototype().As<v8::Object>()->Set(js.v8Context(), foo, > js.num(2))); > > In this case, the Setter configured on the obj prototype is not called > when set via `obj->Set(...)`. > > The question is: with the intended move to `SetNativeDataProperty()` as > communicated via the pending deprecation notice, is this a bug or is the > behavior here intentional? Should setters provided > `PrototypeInstance()->SetNativeDataProperty(...)` Just Work? Or am I just > doing something wrong here? > > -- > -- > v8-dev mailing list > v8-dev@googlegroups.com > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to v8-dev+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/v8-dev/da4aa5ef-d4ae-4b35-ae5c-4946cf8f4d49n%40googlegroups.com > <https://groups.google.com/d/msgid/v8-dev/da4aa5ef-d4ae-4b35-ae5c-4946cf8f4d49n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- Igor Sheludko Software Engineer ish...@google.com Google Germany GmbH Erika-Mann-Straße 33 80636 München Geschäftsführer: Paul Manicle, Liana Sebastian Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Diese E-Mail ist vertraulich. Falls sie diese fälschlicherweise erhalten haben sollten, leiten Sie diese bitte nicht an jemand anderes weiter, löschen Sie alle Kopien und Anhänge davon und lassen Sie mich bitte wissen, dass die E-Mail an die falsche Person gesendet wurde. This e-mail is confidential. If you received this communication by mistake, please don't forward it to anyone else, please erase all copies and attachments, and please let me know that it has gone to the wrong person. -- -- v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-dev+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-dev/CAOAEZ4PmvZQu8kbVdfooX8uifZSe0kyYeZj9gPcVSx7_Eoae7g%40mail.gmail.com.
