Arguments of go rpc. When should they be pointer?

Question

I have read go rpc documentation, and find out one of the 4 criteria:

the method's second argument is a pointer.

The method below shows the right way to use go rpc, thus the second parameter is a pointer *T2.

func (t *T) MethodName(argType T1, replyType *T2) error

Is there any reason for this criteria? Why should it be a pointer?

After I read more examples, find that for most of time, even the first argument is a pointer!

func (t *Arith) Multiply(args *Args, reply *int) error {
    *reply = args.A * args.B
    return nil
}

I know the difference between pointer type and common type, but I'm not sure about it in rpc context.

Answer 1

Reply must be a pointer so the function can assign a value to it.

It is similar to the example here: https://gobyexample.com/pointers