Default Methods in Go · mcyoung

Go's structural typing system for interfaces creates implementation challenges despite its conceptual simplicity. The inability to add default methods to interfaces without breaking existing code leads to messy APIs like flag.Value. A workaround using struct embedding with unexported methods can simulate default implementations by requiring all interface implementors to embed a defaults struct. This technique allows adding new methods to interfaces while maintaining backward compatibility, though it has limitations and ideally should be a language feature.