On Mon, Sep 18, 2017 at 6:13 PM, Zach Bjornson <zbbjorn...@gmail.com> wrote:
>> `myObj.onevent()` invokes `onevent()` with `this === myObj`. Unless
>> you want to deviate significantly from normal JS semantics, you would
>> need to maintain a reference to `myObj` anyway.
>
>
> (The spec I'm emulating actually states that `onevent()` is invoked with the
> global context.) Sorry, I don't think I described the issue well.
>
> The issue is not `onevent` needing to maintain a contextual ref to `myObj`,
> but rather that if `onevent` references `myObj` in its JS function body,
> then `myObj` will not get GC'ed because `onevent`'s function is stored in a
> Persistent handle.
>
> JS:
>
> var myObj = new MyObj();
> myObj.onevent = function () { // (a C++ setter)
> console.log(myObj); // reference to myObj here
> }
> myObj.doSomethingAsync(); // causes `onevent` to fire eventually
>
> C++ (pseudo)
>
> class MyObj : ObjectWrap {
> Persistent<Function> _onevent;
> void setOnEvent(Local<String> prop, const PropertyCallbackInfo<Value>&
> info); // stores fn arg in _onevent
> }
>
> A work-around is to not use C++ for the `onevent` setter, but I'm still
> curious how this would be done in C++. Would the class member be instead a
> Local<Function>, and have to be set with `EscapeableHandleScope
> scope(isolate); _onevent = scope.Escape(functionArg);` (ish)?
>
> Thanks,
> Zach
myObj.onevent is always going to be a strong reference but what you
can do is make myObj strong when myObj.doSomethingAsync() is called,
and weak again when myObj.onevent() is invoked.
Once it's weak again (or when you reset the persistent handle), the
myObj.onevent -> myObj cycle no longer matters, the object will be
eligible for reclamation.
--
--
v8-users mailing list
v8-users@googlegroups.com
http://groups.google.com/group/v8-users
---
You received this message because you are subscribed to the Google Groups
"v8-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to v8-users+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
