On Mon, Aug 19, 2019 at 5:19 PM Sudheer Kumar <kumsudh...@gmail.com> 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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