Struct embedding

Struct embedding in Go allows a struct to include another struct as an anonymous field, automatically promoting its methods and fields to the outer struct's scope. This mechanism enables code reuse and composition without explicit inheritance.

type Animal struct {
    Name string
}

func (a *Animal) Speak() { fmt.Println(a.Name + " speaks") }

type Dog struct {
    Animal // Embedded struct
    Breed  string
}

func main() {
    d := Dog{Animal: Animal{Name: "Buddy"}, Breed: "Poodle"}
    d.Speak() // Output: Buddy speaks
}

Struct embedding lets you build complex types by combining simpler ones, like adding a "battery" component to a "phone" without rewriting the battery code. It matters because it keeps your code DRY (Don't Repeat Yourself) and makes it easier to maintain. You use it whenever you want one object to behave like another while adding its own unique features.