Thank you for the reply, Ben.
> Instead of v8::IndexedPropertyHandlerConfiguration, you may
> want to use v8::NamedPropertyHandlerConfiguration.
>
I am already using it. What I noticed is that, when I run the code without
devtools debugging, only the callback *GenericNamedPropertyGetterCallback,
(*of *NamedPropertyHandlerConfiguration**) *is invoked.
*IndexedPropertyHandlerConfiguration *callbacks are not called even though
they are implemented. But when I run the code through the debugger, I can
see the *IndexedPropertyHandlerConfiguration *callback is called and
whatever I am populating inside it, is visible in the debugger. After that,
*GenericNamedPropertyGetterCallback,
(*of *NamedPropertyHandlerConfiguration**) *is called, for resolving the
names which I am putting into the array in *GenericNamedPropertyGetterCallback
*implementation.
Based on this behaviour, I would assume that *evaluateOnCallFrame *(similar
behaviour is shown by the message *Runtime.getProperties* also, which I
think fetches the variable values for the overlay display) treats the
variable as an indexed property.
regards,
Anoop R. S.
On Thursday, 10 May 2018 13:10:03 UTC+5:30, Ben Noordhuis wrote:
>
> On Thu, May 10, 2018 at 8:42 AM, Anoop R. S. <anoo...@gmail.com
> <javascript:>> wrote:
> > Ok. I figured out that if v8::IndexedPropertyHandlerConfiguration is
> set,
> > and IndexedPropertyEnumeratorCallback is implemented, I can configure
> what
> > is displayed on mouse over action (Debugger.evaluateOnCallFrame is
> passed
> > from devtools on doing that operation.)
> >
> > The implementation is provided below.
> > void IndexedPropertyEnumeratorCallbackFunction(
> > const v8::PropertyCallbackInfo<v8::Array>& p_callbackInfo)
> > {
> > v8::Local<v8::Array> IndexArray =
> > v8::Array::New(p_callbackInfo.GetIsolate(), 2);
> > IndexArray->Set(
> > v8::Integer::New(p_callbackInfo.GetIsolate(), 0),
> > v8::String::NewFromUtf8(p_callbackInfo.GetIsolate(), u8"x"));
> > IndexArray->Set(
> > v8::Integer::New(p_callbackInfo.GetIsolate(), 1),
> > v8::String::NewFromUtf8(p_callbackInfo.GetIsolate(), u8"y"));
> > p_callbackInfo.GetReturnValue().Set(IndexArray);
> > }
> >
> > From reading the embedder's guide, my understanding is that
> >>
> >> indexed property interceptors - called when accessing indexed
> properties.
> >> An example of this, in a browser environment, is
> document.forms.elements[0].
> >
> >
> > Why is it called on evaluateOnCallFrame action? Also, I tried with other
> > callback s of v8::IndexedPropertyHandlerConfiguration, but they are not
> > called. Can I know why? Also, since the signature of callback is as
> below :
> >
> > void (*IndexedPropertyEnumeratorCallback)( const
> > PropertyCallbackInfo<Array>& info);
> >
> > I can set only arrays into the result and nothing else.
> > I am not an expert in v8, hence these questions. Please let me know
> about
> > it/ point me to some documentation regarding this.
> >
> > regards,
> > Anoop R. S.
>
> IndexedPropertyEnumeratorCallback - is called for Object.keys()-like
> operations; i.e., to list the enumerable properties of the object but
> not non-enumerable or prototype properties. The 'Indexed' refers to
> the fact that it's intended for numeric keys, i.e., array-like
> objects. Instead of v8::IndexedPropertyHandlerConfiguration, you may
> want to use v8::NamedPropertyHandlerConfiguration.
>
> evaluateOnCallFrame - V8 cannot know whether your callback has any
> side effects (it could create objects, call into JS code, etc.), hence
> it evaluates it as if it were a snippet of regular JS code. Newer
> versions of V8 let you register callbacks with kHasNoSideEffect but as
> far as I know that has no effect (hah!) on whether or not
> evaluateOnCallFrame is used. Maybe in the future.
>
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