Correct way to create a V8::Persistent

Question

I just upgraded my V8 version to 3.20.16 (from some very old version). I can no longer use

Handle<Object> obj /* = ... */;
Persistent<Object> p = Persistent<Object>::New( obj );

to create a persistent handle to an object. The compiler suggests using static T* v8::Persistent<T>::New(v8::Isolate*, T*) [with T = v8::Object] instead. However, if I change my code to

Handle<Object> obj /* = ... */;
Persistent<Object> p = Persistent<Object>::New( Isolate::GetCurrent(), *obj );

the compiler complains that this function is private. How do I create a Persistent<Object> handle from a normal Handle<Object> now?

I've googled and the only thing I found was that the documentations seem to contradict each other:

https://developers.google.com/v8/embed#handles says that persistent handles are now created using the Persistence constructor
http://bespin.cz/~ondras/html/classv8_1_1Persistent.html indicates that Persistence<T>::New is still the way to go

thanks for any help in advance

score 5 · Accepted Answer · answered Aug 20 '13 at 15:14

5

There is a constructor that accepts normal Handle<T> you don't need to dereference it.

Persistent<Object>::New(Isolate::GetCurrent(), obj)

should work.

answered Aug 20 '13 at 15:14

Vyacheslav Egorov

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Yep, that did it, got confused as there is also no longer a public assignment operator and I had used that in the same line where I used the constructor. For cases where the `Persistent`-Handle already exists, `Persistent.Reset()` can be used. – DeX3 Aug 21 '13 at 07:07
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I end up getting this page many times when I try to find out how to convert v8::Persistent to v8::Local. Here is how. `Persistent perMyFunc; Local localMyFunc = Local::New(isolate, perMyFunc);` – yoshi Feb 21 '14 at 03:17
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If anyone is having a similar issue with more recent versions of V8 and this doesn't work, try [this answer](http://stackoverflow.com/a/22648552/1144176). – Jake Stoeffler Apr 02 '14 at 04:23

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