Do we need wrapper_?

[gabrielschulhof]

In our ObjectWrap N-API examples we store the napi_ref returned from napi_wrap() in the native object instance although we never use it. To napi_delete_reference() in the destructor we need to also store the napi_env on the native instance – a practice we discourage.

Do we do this for illustration purposes? Can we remove this, since wrapper_ is not being used anywhere?

[gabrielschulhof]

This is the extent to which we use wrapper_ and env_:

node-addon-examples/6_object_wrap/napi/myobject.cc

Lines 6 to 11 in dc86a66

	MyObject::MyObject(double value)
	: value_(value), env_(nullptr), wrapper_(nullptr) {}
	MyObject::~MyObject() {
	napi_delete_reference(env_, wrapper_);
	}

and

node-addon-examples/6_object_wrap/napi/myobject.cc

Lines 72 to 78 in dc86a66

	obj->env_ = env;
	status = napi_wrap(env,
	jsthis,
	reinterpret_cast<void*>(obj),
	MyObject::Destructor,
	nullptr, // finalize_hint
	&obj->wrapper_);

[gabrielschulhof]

Compare with the Nan implementation. The use of the persistent reference may stem from there. If so, it may be a good time to diverge, especially since we document that we discourage storing the napi_env.

[gabrielschulhof]

In fact, none of the Nan examples store a persistent reference to the JS instance. We should remove it.