Golang Callback Functions Explained

In Golang, callback functions can be passed as parameters to other functions using function types, and then called when needed.

First, you need to define a function type that represents the signature of the callback function. For example, if your callback function takes an integer as a parameter and returns an integer, you can define the function type as follows:

type CallbackFunc func(int) int

Next, you can write a function that takes a callback function as a parameter and calls it when needed. For example, the following example code defines a function called Process that takes an integer x and a callback function called callback as parameters, then passes x as an argument to the callback function and prints the returned result.

func Process(x int, callback CallbackFunc) {
    result := callback(x)
    fmt.Println(result)
}

Finally, you can define a callback function and then use it by calling the Process function. For example, the following sample code defines a callback function called “double” that multiplies an incoming integer by 2:

func double(x int) int {
    return x * 2
}

Next, you can invoke the Process function by passing an integer and a callback function as parameters.

Process(10, double)

In this way, the Process function will call the double function and print the result, which is 20.

In summary, the steps for using callback functions in Golang can be summarized as:

1. Function type that defines a callback function.
2. Write a function that takes a callback function as a parameter.
3. Create a callback function.
4. Invoke the function and pass a callback function as a parameter.