How to implement interface in golang

Golang is a very popular statically typed, concurrency-safe programming language. It provides a very powerful interface mechanism that allows developers to modularize and decouple code. In this article, we will explore how to implement interfaces using Golang.

What is an interface

Interface is a very important concept in object-oriented programming. An interface defines the set of methods an object should have without actually implementing these methods. This design pattern can make the code more loosely coupled and have better scalability and maintainability. In Golang, an interface is a type that can consist of one or more methods. An interface defines a set of behaviors rather than implementation details. Types that implement an interface can be any type as long as they contain all the methods defined by the interface.

Define interface

In Golang, defining an interface is very simple and straightforward. We just need to define a set of function signatures. The following is an example that defines an interface for measuring the area and perimeter of geometric figures:

type Geometry interface {
    Area() float64    
    Perimeter() float64
}

In the above code, we can see that the Geometry interface defines two methods: Area() and Perimeter (). Any type can become an instance of the Geometry interface type as long as it implements these two methods. Interface names usually end with "er" or are named after the interface's functionality. For the above code, we can name the interface "Geometry", which means that the area and perimeter of any geometric figure can be measured.

Implementing the interface

When we create an interface, we need to create a structure type to implement all the methods defined in the interface. Below is a simple example that implements the Circle and Rectangle types of the Geometry interface.

type Circle struct {
    radius float64
}

type Rectangle struct {
    width  float64
    height float64
}

func (c Circle) Area() float64 {
    return math.Pi * c.radius * c.radius
}

func (r Rectangle) Area() float64 {
    return r.width * r.height
}

func (c Circle) Perimeter() float64 {
    return 2 * math.Pi * c.radius
}

func (r Rectangle) Perimeter() float64 {
    return 2 * (r.width + r.height)
}

In the above code, we defined two types, Circle and Rectangle, that implement all methods of the Geometry interface respectively. For the Circle type, it implements methods for calculating area and perimeter, using floating point numbers to represent properties such as radius, perimeter, and area of ​​a circle. For the Rectangle type, it implements methods for calculating area and perimeter, using floating point numbers to represent the width, height, area, and perimeter of the rectangle.

Using interfaces

After implementing the interface, we can use the type assertion and type assignment provided in Golang to determine whether an object implements an interface. Below is an example that demonstrates how to use the interface to measure the area and perimeter of different geometric shapes.

func main() {
    var g Geometry

    g = Circle{radius: 5}
    measure(g)

    g = Rectangle{width: 3, height: 4}
    measure(g)
}

func measure(g Geometry) {
    fmt.Println("Area:", g.Area())
    fmt.Println("Perimeter:", g.Perimeter())
}

First, we define a variable g, of type Geometry, which can hold any type that implements the Geometry interface. Next, we create a Circle and a Rectangle object and assign them to g. Finally, we call the measure() function, which accepts a parameter of type Geometry. When the measure() function is called, it automatically calls the methods of objects that implement the Geometry interface to calculate the area and perimeter of the geometric shape.

Summary

In this article, we introduced the interface mechanism in Golang. We discussed how to define and implement interfaces and use objects that implement the interfaces to implement area and perimeter calculations. Interfaces are a very powerful feature in Golang, which can make the code easier to read, understand and extend. Therefore, mastering the Golang interface mechanism is an essential skill to become an excellent Golang programmer.

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