Comparative analysis of function passing as value and reference in Golang function

With the development of the Internet and computer technology, the demand for programming languages ​​has gradually increased. In recent years, Golang has become one of the preferred languages ​​for developers. As a compiled language, Golang has efficient and stable execution speed, so it is widely used in web application development and distributed system construction. In Golang, function passing of functions has always been an important concept. Function passing of functions can be used as value or reference. This article will analyze and compare these two delivery methods.

1. Passing functions as values ​​

Passing functions as values ​​means that when a function is passed as a parameter to another function, a copy of the function is passed. This means that if you modify the copy of the function in the parameters, the original function will not be affected. Here is an example of using a function passed as value:

package main

import "fmt"

func main() {
    var f func(string) string
    f = func(msg string) string {
        return "Hello " + msg
    }
    fmt.Println(greet(f, "world"))
}

func greet(f func(string) string, msg string) string {
    return f(msg)
}

In this example, we pass the function "f" as a parameter to the function "greet". So, we can call function "f" inside function "greet" to get the output of "Hello world". This approach is very useful because we can dynamically pass different functions in the code, allowing for more flexible programming. However, it should be noted that when we pass a function as a value, we cannot modify the state of the original function and its parameters.

2. Passing functions as references

Passing functions as references means that when passing a function as a parameter, the memory address of the function is actually passed. This approach allows us to modify the original function in the address context of the passed arguments. Let's look at an example of using functions passed as references:

package main

import "fmt"

func main() {
    var f func(string) string
    f = func(msg string) string {
        return "Hello " + msg
    }
    modifyFn(&f)
    fmt.Println(f("world"))
}

func modifyFn(f **func(string) string) {
    // Update pointer to point to a new function
    *f = newFn
}

func newFn(msg string) string {
    return "Goodbye " + msg
}

In this example, we first create a function "f" and set it to output the string "Hello world". We then pass its address to the function "modifyFn" so that we can modify the state of the function pointer in the function "modifyFn". In the function "modifyFn", we modify the function pointer to a new function "newFn" that outputs the string "Goodbye world". Finally, we execute function "f" again and this time the output is "Goodbye world".

It should be noted that the function pointer needs to be passed through a double pointer ("**") to realize the reference of the function pointer. This reference method allows us to modify the state of the original function, but sometimes it may require more code to achieve.

3. Summary

In Golang, function transfer can be achieved by value or reference. When using a function passed as a value, the state of the original function is not modified, and the code is generally simpler. When passing a function as a reference, you can modify the state of the original function, but the code may be more complex. In practice, the method of transferring the function needs to be chosen according to the specific situation.

The above is the detailed content of Comparative analysis of function passing as value and reference in Golang function. For more information, please follow other related articles on the PHP Chinese website!