How to implement 'inheritance' using composition in Golang

Golang is a powerful and popular programming language that has many unique features, one of which is the implementation of object-oriented programming through composition rather than inheritance. Although Golang does not provide a direct inheritance method, we can still achieve inheritance-like effects through Composition.

In this article, we will introduce how to use composition in Golang to implement "inheritance".

What is object-oriented programming?

Before we start to introduce the implementation of object-oriented programming, we need to first understand what object-oriented programming is. Simply put, object-oriented programming is a programming paradigm. Its main idea is to treat the objects in the program as independent entities and combine their data and behaviors to achieve more flexibility and reliability. Reused code.

The main ideas of object-oriented programming can be simply summarized into the following three aspects:

• Encapsulation: hiding the implementation details of a class inside the class and providing a public interface to the outside world. This is used to protect the data security of the class;
• Inheritance: By inheriting subclasses, the code of the parent class can be reused and expanded on this basis;
• Polymorphism: objects of the same type , can show different behaviors on different occasions.

For Golang, although it supports object-oriented programming, it does not provide traditional inheritance. This is because the designers of Golang believe that inheritance may lead to a tightly coupled class hierarchy. This tight coupling can easily lead to code bloat and difficult maintenance problems in large projects. The alternative to inheritance is to reuse code through Composition.

Implementation of Composition

Composition means that an object "contains" other objects and achieves code reuse through combination. In Golang, we can use Struct to implement Composition.

Let's take a look at how to use Composition to simulate inheritance.

Suppose we have two structures:

type Animal struct {
    Name string
    Age  int
}

type Dog struct {
    Animal
    Breed string
}

In this example, the Animal structure represents an animal and contains two attributes: Name and Age. The Dog structure contains a field of Animal type, and a Breed attribute is added. This method achieves an inheritance-like effect through combination.

We can use the following method to initialize a Dog object:

dog := Dog{
    Animal: Animal{Name: "大黄", Age: 2},
    Breed:  "拉布拉多",
}

fmt.Println(dog.Name, dog.Age, dog.Breed)

In the above example, we created a new Dog object, which contains an Animal object, and set its Name, Age and Breed properties. Then we print out these properties, and the output is as follows:

大黄 2 拉布拉多

From the output, we can see that the Name and Age properties of the Dog object are inherited from the Animal object, and including them achieves something similar to inheritance. Effect.

But it should be noted that the Dog structure does not inherit from the Animal structure, but is implemented by combining the Animal structure.

In other words, we can use Composition to define more complex class hierarchies. For example, we can define a structure to represent humans, which contains a structure named Heartbeat. The Heartbeat structure represents a heartbeat.

type Heartbeat struct {
    rate int
}

func (h *Heartbeat) SetRate(rate int) {
    h.rate = rate
}

func (h *Heartbeat) GetRate() int {
    return h.rate
}

type Human struct {
    Name     string
    Age      int
    Heartbeat Heartbeat
}

In the Human structure, we include a Heartbeat structure and make Heartbeat a field of the Human structure. In this way, we can access the methods of the Heartbeat structure inside the Human structure and set and obtain the heartbeat value.

Summary

Although Golang does not provide a traditional inheritance method, we can achieve an inheritance-like effect by using Composition. Using Composition, we can build a more concise and flexible class hierarchy, making it easier to maintain and expand code in large projects. At the same time, Composition, like other features of object-oriented programming, can also help us write more efficient and reusable code.

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