Mastering Go - Second Edition

Using a Go interface

This subsection will teach you how to use the interface defined in myInterface.go in a Go program named useInterface.go, which will be presented in five parts.

The first part of useInterface.go comes with the next Go code:

package main 
 
import ( 
    "fmt" 
    "math" 
    "myInterface" 
) 
 
type square struct { 
    X float64 
} 
 
type circle struct { 
    R float64 
} 

As the desired interface is defined in its own package, it should come as no surprise that you are importing the myInterface package.

The second code portion from useInterface.go contains the following code:

func (s square) Area() float64 { 
    return s.X * s.X 
} 
 
func (s square) Perimeter() float64 { 
    return 4 * s.X 
} 

In this part, you implement the shape interface for the square type.