Focus on the format of Golang methods

Golang is a programming language that has emerged in recent years. It has the advantages of simplicity, efficiency, and strong concurrency. It is widely used in back-end development, cloud computing and other fields. In Golang, method is a very important programming concept. It can be defined on structures, interfaces and other types to complete specific tasks. In this article, we will focus on the format of Golang methods.

1. Define method

The method definition format in Golang is as follows:

func (receiver type) methodName(parameterList) (returnTypeList) {
    // Code goes here
}

Among them, receiver represents the type to which the method belongs, which can be any type, including Custom structures, etc.; methodName is used to specify the name of the method; parameterList represents the parameter list of the method, which can be any type or empty; returnTypeList represents the type list of the method return value.

2. Receiver type

In Golang, the receiver type is an important part of the method. It can be a pointer type or a value type, depending on the developer's needs.

Value type receiver definition:

type Type struct {
    property int
}
func (t Type) MethodName() ReturnType {
    // Code goes here
}

The methods of a value type receiver can be implemented by creating a value type object and calling the method.

Pointer type receiver definition:

type Type struct {
    property int
}
func (t *Type) MethodName() ReturnType {
    // Code goes here
}

Methods of a pointer type receiver can be implemented by creating a pointer to the type object and calling the method. It should be noted that if the value of the type object needs to be changed in the method, a pointer type receiver must be used.

3. Method parameters and return values

The parameters and return values ​​of methods can be of any type, including built-in types, custom structures, etc. There can be multiple parameters and return values. If there is no return value, it can be omitted.

Method parameter definition:

type Type struct {
    property int
}
func (t *Type) MethodName(param1 string, param2 int) ReturnType {
    // Code goes here
}

Method return value definition:

type Type struct {
    property int
}
func (t *Type) MethodName() (ReturnType1, ReturnType2, error) {
    // Code goes here
}

It should be noted that if the method returns only one value, the parentheses can be omitted.

4. Calling method

In Golang, the format of calling method is as follows:

variable.MethodName(param1, param2)

where variable represents the object to which the method belongs, and MethodName is the method The name, param1 and param2 are the parameter list of the method.

If the variable is a pointer type, you need to use the "*" symbol to dereference:

obj := &Type{}
obj.MethodName(param1, param2)

If the variable is a value type, you do not need to use the dereference symbol:

obj := Type{}
obj.MethodName(param1, param2)

5. Sample code

The following is a complete sample code to demonstrate the definition and calling of Golang methods:

package main

import (
    "fmt"
)

type Rectangle struct {
    length, width float64
}

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

func (r *Rectangle) ScaleLength(factor float64) {
    r.length = r.length * factor
}

func main() {
    r := Rectangle{length: 5.0, width: 3.0}
    fmt.Println("Rectangle Area:", r.Area())

    r.ScaleLength(1.5)
    fmt.Println("Rectangle new length:", r.length)
}

In this example, we define a Rectangle structure Body, which contains two attributes: length and width. Then we define two methods: Area is used to calculate the area of ​​the rectangle, and ScaleLength is used to scale the length of the rectangle proportionally. Finally, a Rectangle object is created in the main function and the above two methods are called.

6. Summary

This article focuses on the definition format of Golang methods, including receiver types, method parameters and return values, method calls, etc. As a core feature of Golang, methods play an important role in daily programming work, and it is very necessary to master their definition and calling methods. I hope this article will be helpful to your mastery of Golang methods.

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