Inheritance

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package main

import (
	"fmt"
)

type People struct {
	name  string
	age   int
}

func (people People) Hello() string {
	return `Hi! I am ` + people.name
}

func main() {
	yu := People{`Yu`, 18}

	fmt.Println(yu.Hello()) // Hi! Someone, I am Yu
}
  • 假設想要有新的結構是 Taiwanese 繼承 People ，寫法是這樣的：
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package main

import (
	"fmt"
)

type People struct {
	name  string
	age   int
}

type Taiwanese struct {
	People
	country  string
}

func (people People) Hello() string {
	return `Hi! I am ` + people.name
}

func main() {
	yu := Taiwanese{People{`Yu`, 18}, `Taiwan`}

	fmt.Println(yu)         // {{Yu 18} Taiwan}
	fmt.Println(yu.country) // Taiwan

	fmt.Println(yu.name)    // Yu
	fmt.Println(yu.age)     // 18
	fmt.Println(yu.Hello()) // Hi! I am Yu

	// 指定結構
	fmt.Println(yu.People.name)    // Yu
	fmt.Println(yu.People.age)     // 18
	fmt.Println(yu.People.Hello()) // Hi! I am Yu
}
  • 可以多重繼承，但若成員重覆的話，就會出現 ambiguous selector 編譯錯誤
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package main

import (
	"fmt"
)

type People struct {
	name  string
	age   int
}

type Animal struct {
	name  string
}

type Taiwanese struct {
	People
	Animal
	country  string
}

覆寫成員與方法

  • 第一個例子可以看到成員與方法是會被繼承下來的，也可以被覆寫：
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package main

import (
	"fmt"
)

type People struct {
	name string
	age  int
}

type Taiwanese struct {
	People
	name    string
	country string
}

func (people People) Hello() string {
	return `Hi! I am ` + people.name
}

func (taiwanese Taiwanese) Hello() string {
	return `你好！我是` + taiwanese.name
}

func main() {
	yu := Taiwanese{People{`Yu`, 18}, `妤`, `Taiwan`}

	fmt.Println(yu.Hello())        // 你好！我是妤
	fmt.Println(yu.People.Hello()) // Hi! I am Yu
}

  • Taiwanese 看起來很像 People 了，不過還是不能當作是 People 使用（多型），要使用 interface 之後才能解決。