Ok. Always good hearing it from the horse's mouth directly. Thanks a lot!
:)
On Tuesday, October 13, 2020 at 8:29:51 PM UTC+2 Ben Noordhuis wrote:
> On Tue, Oct 13, 2020 at 3:37 PM Elling B <elling....@gmail.com> wrote:
> >
> > I found this helper method in a tutorial a couple of days ago.
> >
> > It reinterpret casts a v8::Persistent to a v8::Local, with the intended
> use of calling V8 API functions that require a local handle to a context,
> without actually having to create a new v8::Local each time:
> >
> > template <class TypeName>
> > inline v8::Local<TypeName> ToLocal(const v8::Persistent<TypeName>&
> persistent)
> > {
> > return
> *reinterpret_cast<v8::Local<TypeName>*>(const_cast<v8::Persistent<TypeName>*>(&persistent));
> > }
> >
> > I'm new to V8, so I find myself wondering if it's safe or not. Or if it
> can be safe in some cases.
>
> Full disclosure: that StrongPersistentToLocal() helper from the
> article is my code. I introduced that trick in the Node.js code base
> years ago and looks like people copied it. Mea culpa. :broken_smile:
>
> So, it works, but it's not particularly safe. Caveats:
>
> - don't use it on weakly persistent handles, only strong ones, and
>
> - don't call .Reset() while the Local is still in use
>
> Node.js (ab)uses it for performance reasons but most of the time you
> should just use `Local<Value>::New(isolate, persistent)`.
>
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