这里是带有接口，父结构和2个子结构的Go代码示例

package main

import (
    "fmt"
    "math"
)

// Shape Interface : defines methods
type ShapeInterface interface {
    Area() float64
    GetName() string
    PrintArea()
}

// Shape Struct : standard shape with an area equal to 0.0
type Shape struct {
    name string
}

func (s *Shape) Area() float64 {
    return 0.0
}

func (s *Shape) GetName() string {
    return s.name
}

func (s *Shape) PrintArea() {
    fmt.Printf("%s : Area %v\r\n", s.name, s.Area())
}

// Rectangle Struct : redefine area method
type Rectangle struct {
    Shape
    w, h float64
}

func (r *Rectangle) Area() float64 {
    return r.w * r.h
}

// Circle Struct : redefine Area and PrintArea method 
type Circle struct {
    Shape
    r float64
}

func (c *Circle) Area() float64 {
    return c.r * c.r * math.Pi
}

func (c *Circle) PrintArea() {
    fmt.Printf("%s : Area %v\r\n", c.GetName(), c.Area())
}

// Genreric PrintArea with Interface
func  PrintArea (s ShapeInterface){
    fmt.Printf("Interface => %s : Area %v\r\n", s.GetName(), s.Area())
}

//Main Instruction : 3 Shapes of each type
//Store them in a Slice of ShapeInterface
//Print for each the area with the call of the 2 methods
func main() {

    s := Shape{name: "Shape1"}
    c := Circle{Shape: Shape{name: "Circle1"}, r: 10}
    r := Rectangle{Shape: Shape{name: "Rectangle1"}, w: 5, h: 4}

    listshape := []c{&s, &c, &r}

    for _, si := range listshape {
        si.PrintArea() //!! Problem is Witch Area method is called !! 
        PrintArea(si)
    }

}

我有结果：

$ go run essai_interface_struct.go
Shape1 : Area 0
Interface => Shape1 : Area 0
Circle1 : Area 314.1592653589793
Interface => Circle1 : Area 314.1592653589793
Rectangle1 : Area 0
Interface => Rectangle1 : Area 20

我的问题是对Circle和Rectangle调用Shape.PrintArea哪种调用Shape.Area方法，而不是调用Circle.Area和Rectangle.Area方法。

这是Go中的错误吗？

谢谢你的帮助。