Let's talk about the concept of interfaces in golang

Golang is a brand new programming language whose design focuses on simplicity, efficiency, and security. In Golang, interface is a very important concept. It can be used to define specifications, implement polymorphism, and encapsulate implementation details. This article will introduce the concept, syntax and usage of interfaces in Golang so that readers can better understand and use the language.

1. Golang interface concept

An interface is an abstract type used to define the behavior specification of an object. An interface defines the signatures of a set of methods, and any type that implements these methods can be called an implementation type of the interface. The interface consists of two parts: static type and dynamic type, where the static type refers to the type definition of the interface, and the dynamic type refers to the specific implementation type of the interface.

The interface in Golang has many advantages compared with other programming languages, such as:

1. Simple implementation: The interface in Golang is very simple, just define a set of method signatures That’s it.
2. Easy to call: Because the interface is an abstract type, polymorphic calling can be easily implemented.
3. Strong scalability: The interface can be implemented by any type, so it has good scalability.

2. Golang interface syntax

In Golang, defining an interface is very simple. You only need to use the type and interface keywords. The specific syntax is as follows:

type 接口名 interface{
    方法1(参数列表) 返回值列表
    方法2(参数列表) 返回值列表
    …
}

Among them, the interface name is an identifier defined by the user name, and the method is a set of function signatures. The interface syntax in Golang is very flexible, and the parameter list and return value list in the method can be defined as needed.

Below, let’s look at a simple example:

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

In this example, we define an interface named Shape, including two methods: Perimeter() and Area() . It can be seen that the Perimeter() method returns the perimeter of type float64, while Area() returns the area of ​​type float64.

3. How to use Golang interface

In Golang, we can define type specifications by implementing one or more interfaces. The method of using the interface is as follows:

1. Define the interface

Before implementing an interface, we need to define an interface first. As mentioned earlier, an interface can define a set of methods through which the functionality of the interface is described. In Golang, defining an interface is very simple, just use the type and interface keywords.

2. Implementing the interface

The process of implementing an interface is to standardize a certain type of behavior so that it conforms to the defined interface specification. When a type uses the method signature defined by an interface, it becomes said to implement the interface. In Golang, the implementation interface can be implemented in the following way:

type Circle struct{
    radius float64
}

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

func(circle Circle) Area() float64{
    return math.Pi * math.Pow(circle.radius, 2)
}

In this example, we created a structure named Circle, which contains a radius attribute. In addition, we also defined two methods, Perimeter() and Area(), to implement the requirements of the Shape interface.

3. Using interfaces

In Golang, we can implement polymorphic calling methods by using interfaces. Specifically, we can point an interface type variable to a certain type and then call the interface method implemented by that type. For example:

func main(){
    var shape Shape
    shape = Circle{radius: 2}
    fmt.Println(shape.Perimeter(), shape.Area())
}

In this example, we create an interface variable of type Shape and point it to a structure type Circle. Since Circle implements the methods specified by the Shape interface, this program can output the perimeter and area of ​​the Circle.

4. Golang interface case

Finally, let’s take a look at a complete Golang interface case: implementing a calculator. The following is the code implementation:

type Calculator interface{
    Add(a, b float64) float64
    Sub(a, b float64) float64
    Mul(a, b float64) float64
    Div(a, b float64) float64
}

type Cal struct{}

func(cal Cal) Add(a, b float64) float64{
    return a + b
}

func(cal Cal) Sub(a, b float64) float64{
    return a - b
}

func(cal Cal) Mul(a, b float64) float64{
    return a * b
}

func(cal Cal) Div(a, b float64) float64{
    if b == 0 {
        return 0
    }
    return a / b
}

func main(){
    var cal Calculator
    cal = Cal{}
    fmt.Println(cal.Add(1,2), cal.Sub(3,1), cal.Mul(2,3), cal.Div(9,3))
}

In this example, we define an interface named Calculator and define four Add(), Sub(), Mul() and Div() inside it method. We also created a structure named Cal and implemented all the methods required by the Calculator interface. In the main function, we define an interface variable named cal and point it to the Cal structure. Since Cal implements all methods in the Calculator interface, we can output the results of addition, subtraction, multiplication and division through this variable.

In short, the interface in Golang is a very convenient tool that can play a very good role in standardization, encapsulation and expansion in code design. Through the introduction of this article, we believe that you have understood the concept, syntax and usage of Golang interface. We believe that in actual programming, you will also become more proficient in mastering this tool.

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