任何人都可以解释为什么调用a.Abs()有效吗？在我看来,'a'是*Vertex类型的变量,但*Vertex类型不实现Abs方法.
package main
import (
"fmt"
"math"
)
type Abser interface {
Abs() float64
}
func main() {
var a Abser
v := Vertex{3, 4}
a = &v // a *Vertex implements Abser
// In the following line, v is a *Vertex (not Vertex)
// and does NOT implement Abser, but why does this calling work?
fmt.Println(a.Abs())
}
type Vertex struct {
X, Y float64
}
func (v Vertex) Abs() float64 {
return math.Sqrt(v.X*v.X + v.Y*v.Y)
}