I am implementing an application layer network protocol which uses JSON in Go.
func ReadMessage(conn net.Conn, returnMessage interface{}) bool {
messageBytes := // read from conn
error := json.Unmarshal(messageBytes, &returnMessage)
if error != nil {
return false
}
return true
}
The function takes a struct as its second parameter where the message is unmarshalled. The function can be called like this:
msg := MessageType1{}
ok := ReadMessage(conn, &msg)
Or without the ampersand (&)
msg := MessageType1{}
ok := ReadMessage(conn, msg)
which will compile, but not do what is should as the struct is passed as a copy, not as a reference and the original msg will remain empty. So I'd like to force passing the struct by reference and catch this error at compile time.
Changing the parameter type to *interface{} will not compile:
cannot use &msg (type *MessageType1) as type *interface {} in function argument:
*interface {} is pointer to interface, not interface
Is there some Go style way of doing this correctly?