What's the recommended way to check if a receiver is frozen?

[tavianator]

In a define_method() callback, I want to check if the current object is frozen and avoid mutating it if so. In ankane/faiss-ruby#7, I came up with

define_method("method", [](Rice::Object wrapper) {
  if (wrapper.is_frozen()) {
    throw Rice::Exception{rb_eFrozenError, "can't modify frozen T"};
  }
  auto& self = *Rice::Data_Object<T>{wrapper};
  self.method();
}

Is that the best way to do it? I tried

[](Rice::DataObject<T> wrapper) { ...

but it told me Type is not defined with Rice: Rice::Data_Object<T>.

[cfis]

You can either pass a Ruby object (so the parameter has a type of Object or VALUE) or you can pass a C++ object.

Looking at the PR, you would do like you have:

[](Object wrapper)
{
  ...etc...
}

Or lower level but avoids the Object wrapper:

[](VALUE wrapper)
{
  bool isFrozen = Rice::detail::protect(RB_OBJ_FROZEN, wrapper);
  etc...
}, Arg("wrapper").setValue()

Or:

[](faiss::Index& self)
{
  Data_Object<faiss::Index> wrapper(self);
  ...etc...
}

Most of the time you would pass the C++ instance since you are probably calling a C++ method. But in your case you are calling a Ruby method. So the easiest is what you have done using Object and the more performant version (just because it avoids an Object allocation) is use VALUE.