Any way to use a FnMut with add_method?

[Kampfkarren]

I want to use the following code:

	io.add_method("initialize", |_| {
		check_initialized!(state);
		state.initialized = true;
		Ok(rpc::Value::String("DONE".to_string()))
	});

This gives me the error:

32 |     io.add_method("initialize", |_| {
   |        ----------               ^^^ this closure implements `FnMut`, not `Fn`
   |        |
   |        the requirement to implement `Fn` derives from here
33 |         check_initialized!(state);
34 |         state.initialized = true;
   |         ----- closure is `FnMut` because it mutates the variable `state` here

I'm not sure how to resolve this. I'm new to Rust.

[tomusdrw]

@Kampfkarren the methods can be called by multiple threads, os they have to be Sync. Please wrap any mutability into RwLock, Mutex or use Atomic* structs.