How to get ObjectTemplate in a previous created context?

[Jian Guo]

I want to wrap a javascript class in v8 embedded.

v8::Persistent<v8::Context> persistentContext;
v8::Isolate *pIsolate;
void init() {
    v8::V8::InitializeICU();
    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();
    pIsolate = v8::Isolate::New(create_params);   
    auto ft = v8::FunctionTemplate::New(pIsolate);
    ft->SetClassName(v8::String::NewFromUtf8(pIsolate, "MyClass"));
    ft->ReadOnlyPrototype();
    ft->SetCallHandler(MyClass::constructorCallback);
    ft->SetLength(1);
    v8::Eternal<v8::FunctionTemplate> v8MyClassConstructor(pIsolate, ft);
    auto global_template = v8::ObjectTemplate::New(pIsolate);
    global_template->Set(v8::String::NewFromUtf8(pIsolate, "MyClass"), v8MyClassConstructor.Get(pIsolate));

    // Enter the context for compiling and running the hello world script.
    v8::Local<v8::Context> context = v8::Context::New(pIsolate, nullptr, global_template);
    persistentContext.Reset(pIsolate, context);
}

In my code, after init() being called, I want to wrap more native class to the previous context, what should I do? I want something like:

void bindClass() {
    auto ctx = persistentContext.Get(pIsolate);
    auto global = ctx->GetGlobalObjectTemplate(); // No such function, trying to get global_template variable from init() method
    auto ft = v8::FunctionTemplate::New(pIsolate);

  ft->SetClassName(v8::String::NewFromUtf8(pIsolate, "Foo"));
  // set up another class called "Foo"
  global->Set(v8::String::NewFromUtf8(pIsolate, "Foo"), ft));

   
}


void main() {
       init();
       // some code here...
       bindClass();   // bind more class to global later...
}

Besides, I am puzzled with the global_template concept here, as it is mentioned in the https://v8.dev/docs/embed#templates sample code:

// Create a template for the global object and set the
// built-in global functions.
Local<ObjectTemplate> global = ObjectTemplate::New(isolate);
global->Set(String::NewFromUtf8(isolate, "log"),
            FunctionTemplate::New(isolate, LogCallback));

// Each processor gets its own context so different processors
// do not affect each other.
Persistent<Context> context = Context::New(isolate, NULL, global);

[Ben Noordhuis]

Once the global object is created, it's created - modifying the
ObjectTemplate post hoc won't do anything.

You can still add properties ad hoc through
context->Global()->Set(...) but they won't show up in other contexts,
of course.