GolangInterface = tập hợp method signatures.
Implicit implementation: struct tự động satisfy interface nếu có đủ methods (không cần implements keyword).
go
// Định nghĩa interface
type Writer interface {
Write([]byte) (int, error)
}
type Stringer interface {
String() string
}
// Struct tự động satisfy interface
type MyWriter struct{}
func (w MyWriter) Write(p []byte) (int, error) {
fmt.Print(string(p))
return len(p), nil
}
// Dùng interface làm tham số — polymorphism
func save(w Writer, data []byte) error {
_, err := w.Write(data)
return err
}
// Empty interface chấp nhận mọi type
func printAny(v any) {
fmt.Println(v)
}interface{} (hoặc any) là empty interface chấp nhận mọi type.
An interface is a set of method signatures.
Implementation is implicit: a struct automatically satisfies an interface if it has all required methods — no implements keyword.
go
// Define an interface
type Writer interface {
Write([]byte) (int, error)
}
type Stringer interface {
String() string
}
// Struct implicitly satisfies the interface
type MyWriter struct{}
func (w MyWriter) Write(p []byte) (int, error) {
fmt.Print(string(p))
return len(p), nil
}
// Use interface as parameter — polymorphism
func save(w Writer, data []byte) error {
_, err := w.Write(data)
return err
}
// Empty interface accepts any type
func printAny(v any) {
fmt.Println(v)
}The empty interface interface{} (or any) accepts any type.