How to implement polymorphism in Golang?

How does polymorphism work in Golang?

In Golang, polymorphism is achieved through interfaces. The ability to use multiple different types of objects in a unified manner can be achieved through interfaces, which allows us to write code and handle the logic of different types of objects more flexibly. Next, this article will introduce the concept of polymorphism in Golang and how to use interfaces to achieve polymorphism, and provide code examples to illustrate its role.

The concept of polymorphism can be understood popularly as "an object-oriented concept that allows a pointer of a subclass type to be assigned to a pointer of a parent class type." In Golang, polymorphism is achieved through the definition of interfaces and methods. An interface defines a set of methods without caring about the implementation of the specific type. Any type can be considered an implementation of the interface as long as it implements all methods defined in the interface.

The definition of the interface uses the keyword "interface" and the method signature, for example:

type Animal interface {
    Speak() string
    Move() string
}

The above code defines an interface named Animal, which contains two methods: Speak() and Move(). Any type that implements these two methods can be considered an implementation of the Animal interface.

Next, let us illustrate the role of polymorphism in Golang through an example.

package main

import "fmt"

type Animal interface {
    Speak() string
    Move() string
}

type Dog struct{}

func (d Dog) Speak() string {
    return "Woof!"
}

func (d Dog) Move() string {
    return "Running"
}

type Cat struct{}

func (c Cat) Speak() string {
    return "Meow!"
}

func (c Cat) Move() string {
    return "Jumping"
}

func main() {
    var animal1 Animal = Dog{}
    var animal2 Animal = Cat{}

    fmt.Println(animal1.Speak()) // Output: Woof!
    fmt.Println(animal1.Move()) // Output: Running

    fmt.Println(animal2.Speak()) // Output: Meow!
    fmt.Println(animal2.Move()) // Output: Jumping
}

In the above code, we define the Animal interface and two structures that implement the interface: Dog and Cat. They all implement the Speak() and Move() methods in the Animal interface.

In the main function, we declare two variables, animal1 and animal2, and their types are both Animal interfaces. We assign instances of Dog{} and Cat{} to these two variables respectively.

Then, we called the Speak() and Move() methods using animal1 and animal2, and printed the return results.

Since the types of animal1 and animal2 are both Animal interfaces, we can handle them through a unified interface and do not need to care whether the specific type is Dog or Cat. This reflects the advantages of polymorphism, allowing us to write more flexible and reusable code.

To summarize, polymorphism in Golang is implemented through interfaces, allowing objects of different types to be processed in a unified way. By defining interfaces and methods to implement interfaces, we can handle the logic of different types of objects, improving the flexibility and reusability of the code. The above example code clearly demonstrates the role and use of polymorphism in Golang.

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