How to use embedding in Go to achieve an effect similar to inheritance

In Go, there is no "inheritance" in the traditional sense. However, Go has a mechanism similar to inheritance - embedding. Embedding allows one type to include the properties and methods of another type into its own definition to obtain the same behavior and characteristics. In this article, we will discuss how to use embedding in Go to achieve something similar to inheritance.

The syntax of embedded types is as follows:

type MyType struct {
    OtherType
    // MyType 的其他字段
}

Here OtherType is an already defined type. We can access the properties and methods it defines through OtherType.

Let's look at a simple example. Suppose we have a Person type:

type Person struct {
    Name string
    Age int
}

// 定义一个方法
func (p *Person) SayHello() {
    fmt.Printf("Hello, my name is %s, and I'm %d years old.\n", p.Name, p.Age)
}

Now, we want to define a Student type, which needs to have all the properties and methods of Person , and also needs to have its own specific properties and methods. We can achieve this using embedding:

type Student struct {
    Person  // 嵌入 Person 类型
    School  string
}

// 定义一个方法
func (s *Student) Study() {
    fmt.Printf("%s is studying at %s.\n", s.Name, s.School)
}

Now, we can create the Student instance and call its methods:

s := &Student{Person{Name: "John", Age: 20}, "MIT"}
s.SayHello()  // 输出：Hello, my name is John, and I'm 20 years old.
s.Study()     // 输出：John is studying at MIT.

In the above example, we embed Create the Person type and name it s.Person. This means that we can access the properties and methods of Student just like we access the properties and methods of type Person. For example, we can call s.Name to get the name of the student, and we can also call s.Person.Name to get the name of the Person instance corresponding to the student.

Although embedding provides a mechanism similar to inheritance, it is not exactly the same. Embedded types in Go do not become part of the subclass, but become part of its properties. This means that a subtype cannot override methods of an embedded type because the embedded type is neither a subtype nor an interface type. If a subtype needs to modify the behavior of the embedded type, it can do so by adding methods to the subtype.

In practice, we often use embedded types to avoid duplication of code. Using embedding, we can extract code shared by multiple types into a single type and embed that type into other types to reduce code duplication and complexity. Not only does this help improve code maintainability, it also helps us pay more attention to detail when implementing specific features.

In this article, we introduce the embedding mechanism in Go and demonstrate how to use it to achieve inheritance-like behavior. Although the embedding mechanism has its own limitations, it is a powerful tool that can help us minimize code duplication and improve maintainability when developing large projects.

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