Golang interface implementation methods and example analysis

Golang is a statically typed, compiled language originally designed and developed by Google that excels when handling large-scale projects. Interface in Golang is an important concept that allows interoperability between types and supports polymorphism.

Introduction to Golang interface

In Golang, an interface is an abstract type that defines the behavior of an object. An interface consists of a set of method signatures without a specific implementation. By implementing these method signatures, the type satisfies the requirements of the interface. Any type is considered to implement the interface as long as it implements all methods defined by the interface.

Definition of Golang interface

The definition of the interface uses the type keyword, followed by the interface name and method signature. For example:

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

The above code defines an interface Shaper, which has two methods Area() and Perimeter(), The return values ​​are of type float64.

Implementation of Golang interface

To implement an interface, you only need to implement all the methods defined in the interface. The following is a simple example to demonstrate the implementation of the interface:

package main

import (
    "fmt"
)

type Rectangle struct {
    width, height float64
}

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

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

func main() {
    var s Shaper
    r := Rectangle{width: 5, height: 3}
    s = r

    fmt.Println("Area:", s.Area())
    fmt.Println("Perimeter:", s.Perimeter())
}

In the above code, a Rectangle structure is defined and Area() is implemented and Perimeter() method. By assigning the Rectangle type to the interface variable s, the interface is implemented.

Empty interface

Empty interface refers to an interface without method signature, which is equivalent to Object in Java. In Golang, an empty interface can represent any type. The following is an example of an empty interface:

package main

import "fmt"

func describe(i interface{}) {
    fmt.Printf("(%v, %T)
", i, i)
}

func main() {
    var i interface{}

    describe(42)
    describe("hello")
    describe([]int{1, 2, 3})
    describe(struct{ name string }{"Alice"})

    i = 3.14
    fmt.Println(i)
}

In the above code, the describe function accepts a parameter of an empty interface type and prints out the value and type of the parameter. In the main function, call the describe function to pass in different types of parameters.

Nesting of interfaces

Interfaces in Golang support nesting and can be embedded in other interfaces or structures. Nested interfaces can make code more modular and flexible. The following is a sample code using nested interfaces:

package main

import "fmt"

type Reader interface {
    Read()
}

type Writer interface {
    Write()
}

type ReadWriter interface {
    Reader
    Writer
}

type File struct{}

func (f File) Read() {
    fmt.Println("Reading file")
}

func (f File) Write() {
    fmt.Println("Writing file")
}

func main() {
    var rw ReadWriter
    f := File{}
    rw = f

    rw.Read()
    rw.Write()
}

The above code defines three interfaces Reader, Writer and ReadWriter, The ReadWriter interface nests the Reader and Writer interfaces. The File structure implements the Read() and Write() methods, and also implements the ReadWriter interface.

Through the above examples, we can see the definition, implementation and nesting of interfaces in Golang. Interface is a powerful feature in Golang language that can help us write more flexible and extensible code. I hope this article will help you understand the implementation of the Golang interface.

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