Implicit Interface Implementation

Snippet

Implicit Interface Implementation

In Go, interfaces are implemented implicitly. A type satisfies an interface by simply implementing its methods; there is no 'implements' keyword. This decouples the definition of the interface from its implementation.

snippet.go
go
package main
 
import "fmt"
 
type Describer interface {
    Describe() string
}
 
type Product struct {
    Name  string
    Price float64
}
 
func (p Product) Describe() string {
    return fmt.Sprintf("%s costs $%.2f", p.Name, p.Price)
}
 
func main() {
    var d Describer = Product{Name: "Keyboard", Price: 49.99}
    fmt.Println(d.Describe())
}

Breakdown

type Describer interface { ... }

Defines an interface with a Describe method that returns a string.

func (p Product) Describe() string

The Product struct implements the Describe method, satisfying the Describer interface.

var d Describer = Product{...}

A Product instance can be assigned to a Describer variable because it satisfies the interface.

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Implicit Interface Implementation

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