Go语言程序创建抽象类

package main

import "fmt"
// fmt package allows us to print anything on the screen

// Define a new data type "Triangle" and define base and height properties in it
type Triangle struct {
   base, height float32
}

// Define a new data type "Square" and assign length as a property to it.
type Square struct {
   length float32
}

// Define a new data type "Rectangle" and assign length and width as properties to it
type Rectangle struct {
   length, width float32
}

// Define a new data type "Circle" and assign radius as a property to it
type Circle struct {
   radius float32
}

// defining a method named area on the struct type Triangle
func (t Triangle) Area() float32 {
   // finding the area of the triangle
   return 0.5 * t.base * t.height
}

// defining a method named area on the struct type Square
func (l Square) Area() float32 {
   // finding the area of the square
   return l.length * l.length
}

// defining a method named area on the struct type Rectangle
func (r Rectangle) Area() float32 {
   // finding the area of the Rectangle
   return r.length * r.width
}

// defining a method named area on the struct type Circle
func (c Circle) Area() float32 {
   // finding the area of the circle
   return 3.14 * (c.radius * c.radius)
}

// Define an interface that contains the abstract methods
type Area interface {
   Area() float32
}

func main() {
   // Assigning the values of length, width and height to the properties defined above
   t := Triangle{base: 15, height: 25}
   s := Square{length: 5}
   r := Rectangle{length: 5, width: 10}
   c := Circle{radius: 5}

   // Define a variable of type interface
   var a Area

   // Assign to the interface a variable of type "Triangle"
   a = t
   // printing the area of triangle
   fmt.Println("Area of Triangle", a.Area())

   // Assign to the interface a variable of type "Square"
   a = s
   // printing the area of the square
   fmt.Println("Area of Square", a.Area())

   // Assign to the interface a variable of type "Rectangle"
   a = r
   // printing the area of the rectangle
   fmt.Println("Area of Rectangle", a.Area())

   // Assign to the interface a variable of type "Circle"
   a = c
   // printing the area of the circle
   fmt.Println("Area of Circle", a.Area())
}