Go -- 扩展

栏目: Go · 发布时间: 6年前

内容简介：面向对象的扩展可以通过

面向对象的扩展可以通过继承和复合来实现，但 Go 并不支持继承

class Pet {
    public void speak() {
        System.out.println("Pet Speak");
    }
}

class Dog extends Pet {
    @Override
    public void speak() {
        System.out.println("Dog Speak");
    }
}

public class InheritTest {
    @Test
    public void subClassAccessTest() {
        Pet dog = new Dog();
        dog.speak(); // Dog Speak
    }

    @Test
    // LSP : Liskov substitution principle
    // 里氏替换原则：派生类（子类）对象可以在程式中代替其基类（超类）对象
    public void lspTest() {
        makePetSpeak(new Dog()); // Dog Speak
    }

    private void makePetSpeak(Pet pet) {
        pet.speak();
    }
}

Go的扩展

复合

type Pet struct {
}

func (p *Pet) speak() {
    fmt.Println("Pet Speak")
}

type Dog struct {
    // 复合：通过Pet扩展Dog的功能
    p *Pet
}

func (d *Dog) speak() {
    d.p.speak()
    fmt.Println("Dog Speak")
}

func TestComplex(t *testing.T) {
    t.Logf("%T", Dog{})    // extension.Dog
    t.Logf("%T", &Dog{})   // *extension.Dog
    t.Logf("%T", new(Dog)) // *extension.Dog
    dog := new(Dog)
    dog.speak()
    // 输出
    //	Pet Speak
    //	Dog Speak
}

匿名嵌套类型

type Pet struct {
}

func (p *Pet) speak() {
    fmt.Println("Pet Speak")
}

func (p *Pet) eat() {
    fmt.Println("Pet Eat")
}

type Dog struct {
    // 匿名嵌套类型，不能当成继承使用
    Pet
}

func (d *Dog) speak() {
    fmt.Println("Dog Speak")
}

func TestAnonymousNestedType(t *testing.T) {
    dog := new(Dog)
    dog.eat()   // Pet Eat
    dog.speak() // Dog Speak
}

func TestNotInherit(t *testing.T) {
    // 不符合LSP
    // var d1 Pet = new(Dog)         // cannot use new(Dog) (type *Dog) as type Pet in assignment
    // var d2 Pet = Dog{}            // cannot use Dog literal (type Dog) as type Pet in assignment
    // var d3 Pet = (*Pet)(new(Dog)) // cannot convert new(Dog) (type *Dog) to type *Pet
}

以上就是本文的全部内容，希望本文的内容对大家的学习或者工作能带来一定的帮助，也希望大家多多支持码农网

查看所有标签

猜你喜欢:

本站部分资源来源于网络，本站转载出于传递更多信息之目的，版权归原作者或者来源机构所有，如转载稿涉及版权问题，请联系我们。

码农书籍

Refactoring

Martin Fowler、Kent Beck、John Brant、William Opdyke、Don Roberts / Addison-Wesley Professional / 1999-7-8 / USD 64.99

Refactoring is about improving the design of existing code. It is the process of changing a software system in such a way that it does not alter the external behavior of the code, yet improves its int......一起来看看《Refactoring》这本书的介绍吧!

码农工具