golang callback method

Callback function is a common programming method, also in Golang. This article will introduce the concept, usage and examples of callback functions in Golang.

What is a callback function

A callback function refers to a function that is passed as a parameter to another function and is called during the execution of the function. function. Callback functions are usually used to handle some asynchronous or time-consuming operations, such as network requests, file reading and writing, etc. The advantage of the callback function is that it avoids function blocking and improves the execution efficiency of the code.

Basic syntax of callback function

In Golang, the basic syntax of callback function is as follows:

func callback(para1 type1, callbackFunc func(type2) type3) {
    // 进行一些操作
    callbackFunc(value)
}

Among them, callback is a function that performs some operations , para1 is the parameter of the callback function, callbackFunc is the callback function, type2 is the parameter type of the callback function, type3 is the return type of the callback function, value is the parameter of the callback function.

When using a callback function, you can first define the callback function and then pass it as a parameter to other functions, for example:

func main() {
    callback("Hello", func(str string) string {
        return str + " World"
    })
}

func callback(para1 string, callbackFunc func(string) string) {
    // 进行一些操作
    result := callbackFunc(para1)
    fmt.Println(result)
}

The above code defines a callback function, Receives a string type parameter and a callback function, and then splices it into a sentence for output. In the main function, a callback function is defined to concatenate the strings into a complete sentence and pass it as a parameter to the callback function for processing.

Examples of callback functions

The following examples further illustrate the use of callback functions in Golang. Suppose there is a requirement: get the length of a string. Because the length of a string may be a time-consuming operation, we define a callback function to process the length of the string in the callback function.

package main

import (
    "fmt"
    "time"
)

// 回调函数类型
type CallbackFunc func(int)

// 获取字符串长度的函数
func getStringLength(str string, callback CallbackFunc) {
    time.Sleep(1 * time.Second) // 模拟一个耗时的操作
    length := len(str)
    callback(length)
}

// 回调函数的实现
func callbackFunc(length int) {
    fmt.Println("字符串的长度为：", length)
}

func main() {
    getStringLength("Hello World", callbackFunc)
}

In the above code, we define a getStringLength function that receives a string and a callback function as parameters. Inside the function, a time-consuming operation is simulated, that is, waiting for 1 second to obtain the length of the string, and passing the length as a parameter to the callback function.

The implementation of the callback function is completed in the callbackFunc function. When the getStringLength function is executed, the callback function will be automatically called and the length of the string will be passed in as a parameter.

Call the getStringLength function in the main function, passing in the string and callback function as parameters.

Execute the above code, the output result is as follows:

字符串的长度为： 11

Summary

The callback function is a common programming method, which can improve the execution efficiency of the code and avoid function blocking . In Golang, the use of callback functions is similar to that in other programming languages. You need to define the callback function type and the implementation of the callback function. At the same time, you need to pay attention to the execution timing of the callback function to ensure that the callback function can be called correctly.

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