我们知道在传递变量时，尽量使用指针方式能够节约资源，我们来看一下在接口中如何应用指针，我们直接对接口的使用样例的代码进行改造。我们首先将area()的reciver类型修改为指针，再将传递到接口中的变量变为&c1方式，就可以在接口中使用指针。
// Define a new interface, contain a method define and type is float64
type shape interface {
area() float64
}
type rect struct {
width float64
height float64
}
func (r *rect) area() float64 {
return r.width * r.height
}
.....
shapes := []shape{&c1, &r1}
.....完整代码如下
package main
import (
"fmt"
"math"
)
// Define a new interface, contain a method define and type is float64
type shape interface {
area() float64
}
type rect struct {
width float64
height float64
}
func (r *rect) area() float64 {
return r.width * r.height
}
type circle struct {
radius float64
}
func (c *circle) area() float64 {
return math.Pi * c.radius * c.radius
}
func main() {
var areaSum float64
// Intial circle and rect struct type
c1 := circle{2.5}
r1 := rect{3, 4}
// Previous: Save all area results into an array
// Previous: shapeAreas := []float64{c1.area(), r1.area()}
// Define an array with new shape interface
shapes := []shape{&c1, &r1}
// Previous: Sum all area together
areaSum = 0
// Previous: for _, area := range shapeAreas {
// Previous: areaSum += area
// Previous: }
// Implement a new loop
for _, shape := range shapes {
areaSum += shape.area()
}
fmt.Printf("Sum area = %v\n", areaSum)
}