golang中的use-a和has-a

type Person struct {
    Name    string
    Address Address
}

type Address struct {
    Number string
    Street string
    City   string
    State  string
    Zip    string
}

func (p *Person) Talk() {
    fmt.Println("Hi, my name is", p.Name)
}

func (p *Address) Location() {
    //fmt.Println("I'm at", p.Address.Number, p.Address.Street, p.Address.City, p.Address.State, p.Address.Zip)
    fmt.Println("I'm at", p.Number, p.Street, p.City, p.State, p.Zip)
}

func main() {
    p := Person{
        Name: "Steve",
        Address: Address{
            Number: "13",
            Street: "Main",
            City:   "Gotham",
            State:  "NY",
            Zip:    "01313",
        },  
    }

    p.Talk()
    // p.Location() wrong
    p.Address.Location()
}

上面是一个“use-a”代码片段，不过注意“ Address仍然是一个不同的对象，只不过存在于Person中”。

type Person struct {
    Name string
    Address
}

type Address struct {
    Number string
    Street string
    City   string
    State  string
    Zip    string
}

func (p *Person) Talk() {
    fmt.Println("Hi, my name is", p.Name)
}

func (p *Address) Location() {
    //fmt.Println("I'm at", p.Address.Number, p.Address.Street, p.Address.City, p.Address.State, p.Address.Zip)
    fmt.Println("I'm at", p.Number, p.Street, p.City, p.State, p.Zip)
}

func main() {
    p := Person{
        Name: "Steve",
        Address: Address{
            Number: "13",
            Street: "Main",
            City:   "Gotham",
            State:  "NY",
            Zip:    "01313",
        },  
    }   

    p.Talk()
    p.Location()
    p.Address.Location()
}

上面是一个“is-a”代码片段，不过注意“ 通过引入匿名域（Person）实现了is-a关系。Person是Citizen的一个匿名域（anonymous field），匿名域只给出了对象类型，而不给出类型的名字。通过匿名域，Citizen可以访问Person中的所有属性（域）和方法。 ”。

部分代码和文字转自《go是面向对象语言吗？》。

golang中的use-a和has-a

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