Thanks for your reply Ben,
I have tried as you suggested :
context->Global()->SetInternalField(0, obj);
but didn't worked ...
am I doing anything wrong during the initialization ?
On Monday, August 19, 2019 at 11:30:57 PM UTC+5:30, Ben Noordhuis wrote:
>
> On Mon, Aug 19, 2019 at 5:19 PM Sudheer Kumar <kumsu...@gmail.com
> <javascript:>> wrote:
> >
> > Hello everyone,
> > I am struggling wrapping and unwrapping the c++ object (MYCLASS) .
> below is the sample code i have written for my exact requirement:
> >
> >
> > void Update_Rotation(const v8::FunctionCallbackInfo<v8::Value>& info);
> >
> > class MYCLASS {
> > public:
> >
> > Point(D_TYPE1 *par1) : rotate(par1) { }
> >
> > D_TYPE1 *rotate;
> >
> > void run_script()
> > {
> > v8::V8::InitializeICUDefaultLocation(argv);
> > v8::V8::InitializeExternalStartupData(argv);
> > std::unique_ptr<v8::Platform> platform =
> v8::platform::NewDefaultPlatform();
> > v8::V8::InitializePlatform(platform.get());
> > v8::V8::Initialize();
> >
> > v8::Isolate::CreateParams create_params;
> > create_params.array_buffer_allocator =
> v8::ArrayBuffer::Allocator::NewDefaultAllocator();
> > v8::Isolate* isolate = v8::Isolate::New(create_params);
> > v8::Isolate::Scope isolate_scope(isolate);
> >
> > v8::Isolate::Scope isolate_scope(isolate);
> >
> > // Create a stack-allocated handle scope.
> > v8::HandleScope handle_scope(isolate);
> >
> > // Create a template for the global object.
> > v8::Handle<v8::ObjectTemplate> global =
> v8::ObjectTemplate::New(isolate);
> >
> > /* Here the internal field count is set to 1 which means the object has
> one internal field, with an index of 0, that points to a C++ object.*/
> > global->SetInternalFieldCount(1);
> >
> > // Bind the 'update_rotation' function
> > global->Set(v8::String::NewFromUtf8(isolate, "update_rotation",
> v8::NewStringType::kNormal).ToLocalChecked(),
> > v8::FunctionTemplate::New(isolate, Update_Rotation));
> > // Create a new context.
> > v8::Local<v8::Context> context = v8::Context::New(isolate, NULL,
> global);
> > //Persistent<Context> context = v8::Context::New(isolate, NULL, global,
> nullptr);
> >
> > // Enter the context for compiling and running the script.
> > v8::Context::Scope context_scope(context);
> >
> > Local<Object> obj = global->NewInstance(context).ToLocalChecked();
> > obj->SetInternalField(0, External::New(isolate, this));
> > /* My JS script */
> > v8::Local<v8::String> source = v8::String::NewFromUtf8(isolate, "var
> rotate_status =
> update_rotation();",v8::NewStringType::kNormal).ToLocalChecked();
> > //exception handler
> > v8::TryCatch try_catch(isolate);
> >
> > printf("Script : compilation started\n");
> > // Compile the source code.
> > v8::Local<v8::Script> script = v8::Script::Compile(context,
> source).ToLocalChecked();
> > printf("Script : compilation compilation done\n");
> > printf("Script : Running started\n");
> > // Run the script to get the result.
> > v8::Local<v8::Value> result = script->Run(context).ToLocalChecked();
> > }
> > };
> >
> > void Update_Rotation(const v8::FunctionCallbackInfo<v8::Value>& info) {
> > Local<Object> self = info.Holder();
> > Local<External> wrap = Local<External>::Cast(self->GetInternalField(0));
> > void* ptr = wrap->Value();
> > MYCLASS* temp_sp = static_cast<MYCLASS*>(ptr);
> //--> Here i am always getting null pointer
> > D_TYPE1 *rotate_ptr = static_cast<Point*>(ptr)->rotate;
> >
> > rotate_ptr->Update();
> > }
> >
> >
> > int main()
> > {
> > D_TYPE1 *sample_rotate_obj = new D_TYPE1();
> > MYCLASS test_obj(sample_rotate_obj);
> >
> > test_obj.run_script();
> > }
> >
> >
> > Can anyone plz suggest how to fix it to get valid pointer to my object?
> >
> > Thanks in advance ...
> >
> > Regards
> > Sudheer
>
> To summarize what your code does:
>
> 1. It creates an ObjectTemplate for the global template.
> 2. It passes that ObjectTemplate to Context::New()
> 3. It then creates a new instance of the same ObjectTemplate and sets
> its internal field #0.
>
> In other words, two instances are created: once by you, once
> (implicitly) by Context::New().
>
> The one you created manually isn't used. When JS code calls your
> update_rotation() method, it does so using the instance that
> Context::New() created.
>
> I didn't test but calling context->Global()->SetInternalField() might
> fix your issue.
>
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