Introducing the usage of interface in Golang

Go is a strongly typed programming language. Unlike other programming languages, it has an interface type, which allows the signature of one or more methods to be defined, but not implemented. By implementing the methods of this interface, different types of objects with different data types can be assigned to the same interface type and processed, making programming more flexible and extensible.

Let’s introduce the usage of interface in Golang in detail.

Basic concept of interface

In Golang, interface is a way of defining a contract. It defines a set of methods that must be implemented by some objects. When an object implements all methods in an interface, the object is considered to implement the interface. We can define an interface through the keyword interface, and its definition syntax is as follows:

type interface_name interface {
  method_name1 [return_type]
  method_name2 [return_type]
  ...
  method_namen [return_type]
}

Usage of interface

After defining an interface, we can achieve the restriction method by implementing this interface the goal of. The following is a simple example:

package main

import "fmt"

type Printer interface {
    Print()
}
//定义接口

type Hero struct {
    Name    string
    Age     int
    Address string
}//定义一个结构体

func (h *Hero) Print() {
    fmt.Println("Name:", h.Name)
    fmt.Println("Age: ", h.Age)
    fmt.Println("Address: ", h.Address)
}//实现接口

func main() {
    hero1 := &Hero{Name: "Diana Prince", Age: 33, Address: "Washington, D.C."}
    hero1.Print()
}//使用接口

In the above example, we defined the Printer interface, which has only one Print() method, and then we defined a structure Hero to implement Print in the interface () method, and finally we use hero1 to call the Print() method.

Empty interface

The empty interface is an interface that does not contain any methods, which means that it does not need to implement any methods. We can assign any type of value to the empty interface variable.

The empty interface type interface{} can be assigned by any variable, and it can be used as a container for any data type. A function can receive a parameter of an empty interface type and can also return a value of an empty interface type.

Type assertion of interface

When using an empty interface, it is often necessary to convert variables into specific types. Go provides a type assertion mechanism that can check the type of the value pointed to by an interface type variable. .

value, ok := var_interface.(Type_name)

Among them, var_interface represents the interface variable, Type_name is the type that needs to be asserted, value represents the value converted after the assertion is successful, and ok represents whether the assertion is successful.

Combining and embedding interfaces

Interfaces can be combined and embedded to extend the functions of the interface.

type Interface1 interface {
    method1()
}

type Interface2 interface {
    method2()
}

type Interface3 interface {
    Interface1
    Interface2
    method3()
}

In the above example, Interface3 combines Interface1 and Interface2 to have all their methods, and Interface3 can also have its own method method3().

In addition, interface embedding is also supported in Golang.

type Animals interface {
    Name() string
}

type Dog struct {
    Animals //继承接口
}

func (d Dog) Bark() {
    fmt.Println("汪汪汪！")
}

In the above example, we embed the Animals interface and implement the Name() method to realize that Dog inherits the Name() method of Animals after instantiation.

Summary

Interface is a way to define contracts in Golang, which can limit the implementation of methods. The implementation of interfaces allows objects of different types to be processed in the same way. At the same time, the language also provides features such as type assertions, interface combinations, and interface embeddings, making the application of interfaces more flexible and extensible.

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