戈朗的传承
继承是指将超类的属性继承到基类中，是面向对象编程中最重要的概念之一。由于 Golang 不支持类，所以继承是通过结构嵌入实现的。我们不能直接扩展结构，而是使用一个叫做合成的概念，其中结构被用来形成其他对象。所以，你可以说戈朗 有无继承观念。
在组合中，基本结构可以嵌入到子结构中，并且基本结构的方法可以直接在子结构上调用，如下例所示。
例 1:
// Golang program to illustrate the
// concept of inheritance
package main
import (
"fmt"
)
// declaring a struct
type Comic struct{
// declaring struct variable
Universe string
}
// function to return the
// universe of the comic
func (comic Comic) ComicUniverse() string {
// returns comic universe
return comic.Universe
}
// declaring a struct
type Marvel struct{
// anonymous field,
// this is composition where
// the struct is embedded
Comic
}
// declaring a struct
type DC struct{
// anonymous field
Comic
}
// main function
func main() {
// creating an instance
c1 := Marvel{
// child struct can directly
// access base struct variables
Comic{
Universe: "MCU",
},
}
// child struct can directly
// access base struct methods
// printing base method using child
fmt.Println("Universe is:", c1.ComicUniverse())
c2 := DC{
Comic{
Universe : "DC",
},
}
// printing base method using child
fmt.Println("Universe is:", c2.ComicUniverse())
}
输出:
Universe is: MCU
Universe is: DC
当子结构能够访问多个基本结构的多个属性、字段和方法时，就会发生多个继承。这里，子结构嵌入了所有的基本结构，如下面的代码所示:
例 2:
// Golang program to illustrate the
// concept of multiple inheritances
package main
import (
"fmt"
)
// declaring first
// base struct
type first struct{
// declaring struct variable
base_one string
}
// declaring second
// base struct
type second struct{
// declaring struct variable
base_two string
}
// function to return
// first struct variable
func (f first) printBase1() string{
// returns a string
// of first struct
return f.base_one
}
// function to return
// second struct variable
func (s second) printBase2() string{
// returns a string
// of first struct
return s.base_two
}
// child struct which
// embeds both base structs
type child struct{
// anonymous fields,
// struct embedding
// of multiple structs
first
second
}
// main function
func main() {
// declaring an instance
// of child struct
c1 := child{
// child struct can directly
// access base struct variables
first{
base_one: "In base struct 1.",
},
second{
base_two: "\nIn base struct 2.\n",
},
}
// child struct can directly
// access base struct methods
// printing base method
// using instance of child struct
fmt.Println(c1.printBase1())
fmt.Println(c1.printBase2())
}
输出:
In base struct 1.
In base struct 2.
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