gopl-zh.github.com/vendor/gopl.io/ch4/embed/main.go

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2015-12-09 07:45:11 +00:00
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
// See page 106.
// Embed demonstrates basic struct embedding.
package main
import "fmt"
type Point struct{ X, Y int }
type Circle struct {
Point
Radius int
}
type Wheel struct {
Circle
Spokes int
}
func main() {
var w Wheel
//!+
w = Wheel{Circle{Point{8, 8}, 5}, 20}
w = Wheel{
Circle: Circle{
Point: Point{X: 8, Y: 8},
Radius: 5,
},
Spokes: 20, // NOTE: trailing comma necessary here (and at Radius)
}
fmt.Printf("%#v\n", w)
// Output:
// Wheel{Circle:Circle{Point:Point{X:8, Y:8}, Radius:5}, Spokes:20}
w.X = 42
fmt.Printf("%#v\n", w)
// Output:
// Wheel{Circle:Circle{Point:Point{X:42, Y:8}, Radius:5}, Spokes:20}
//!-
}