golang中的use-a和has-a

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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？》。

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