go - Allowing multiple types in arguments to interface method

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/66054446/allowing-multiple-types-in-arguments-to-interface-method

Answer 1

To implement an interface, a type has to implement the methods of the interface. The method MyFunc(interface{}) is different from MyFunc(string), so a type implementing MyFunc(string) does not implement the interface with the method with interface{} arg.

The semantics of the method that takes a string is different from the one that takes an interface{}. First, the method that takes a string cannot get a nil-value, but the one that gets an interface{} does. The calling semantics are also different: To call a function with interface{} argument, the compiler creates an interface{} containing the value and the type of the value you're calling it with. Finally, A type with MyFunc(string) cannot be substituted for a type with MyFunc(interface{}), because the second one can be called with any type of data.