Golang function callback function application explanation

Golang is an efficient programming language, and the application of callback functions of its functions is extremely important. Therefore, in this article, we will explain in depth the relevant knowledge of the application of callback functions of Golang functions.

1. What is a callback function?

The callback function is a function pointer, which is passed directly to other functions as a parameter. When this parameter function is executed, our function will be called back. This is the basic concept of the callback function.

2. The syntax of Golang callback function

In Golang, the syntax of callback function is very simple. You only need to pass the function name as a parameter to other functions. For example:

package main

import "fmt"

func main() {
    // 定义一个函数，并将它作为参数传递给另一个函数
    fm(1,2,func(a,b int) int{
        return a+b
    })
}
// 定义一个函数，调用回调函数
func fm(a,b int, f func(int,int)int) {
    fmt.Println(f(a,b))
}

As you can see, in this code, we define a function fm, which receives three parameters, one of which is a callback function. In the main function, we define a callback function and then pass it as a parameter to the fm function.

3. Application of callback function

1. Asynchronous processing

The callback function can implement asynchronous processing. For example, we need to read 1G of data from the database, and at this time We need the user's operation to continue reading. At this time, we can use the callback function to implement asynchronous processing.

package main

import (
    "fmt"
    "time"
)

func main() {
    // 测试异步处理，开始时间
    start := time.Now()

    // 创建一个异步函数
    go doSomething(func() {
        fmt.Printf("异步处理完成，消耗时间: %s", time.Since(start))
    })

    // 主线程
    fmt.Println("主线程继续执行")
    time.Sleep(time.Second * 4)
}

// 异步函数处理
func doSomething(cb func()) {
    fmt.Println("do something")
    time.Sleep(time.Second * 3)
    cb()
}

In this code, we define a doSomething function, which implements asynchronous processing. When doSomething is completed, the callback function cb can be executed. In the main function, we call the doSomething function and exit after waiting 4 seconds in the main thread. When this program is executed, "do something" and "main thread continues execution" will be output first, and then the wait process will execute the callback function cb after the main thread waits for 3 seconds. So the output structure is:

do something
主线程继续执行
异步处理完成，消耗时间: 3.004536386s

2. Logging

Another common example of using callback functions is in logging applications. For example, if we need to record the log information of a specific event, we can use the callback function to achieve this task.

In this example, we will use the callback function to print the log message directly to the console.

package main

import "fmt"

func main() {
    // 调用打印日志的函数
    logMessage("This is my debug message", func(msg string) {
        fmt.Printf("DEBUG: %s
", msg)
    })
}

// 记录日志（把日志消息通过回调函数输出到控制台上）
func logMessage(msg string, logger func(string)) {
    logger(msg)
}

In the above code implementation, we defined a logMessage function, which accepts a callback function as a parameter and prints the message to the console.

We finally call the logMessage function directly in the main function and pass an anonymous function as a callback parameter. This anonymous function will be called in the logMessage function to output a log message on the console.

4. Summary

In this article, we have an in-depth explanation of the relevant knowledge about the application of callback functions in Golang functions. Starting from what a callback function is, to simple callback function syntax, and then to the application scenarios of various callback functions, I hope this article can be helpful to readers.

The above is the detailed content of Golang function callback function application explanation. For more information, please follow other related articles on the PHP Chinese website!