Mastering Go - Second Edition

Functions that return other functions

In this section, you are going to learn how to implement a Go function that returns another function using the Go code of returnFunction.go, which will be presented in three segments. The first code segment of returnFunction.go is as follows:

package main 
 
import ( 
    "fmt" 
) 
 
func funReturnFun() func() int { 
    i := 0 
    return func() int { 
        i++ 
        return i * i 
    } 
} 

As you can see from the implementation of funReturnFun(), its return value is an anonymous function (func() int).

The second code segment from returnFunction.go contains the following code:

func main() { 
    i := funReturnFun() 
    j := funReturnFun() 

In this code, you call funReturnFun() two times and assign its return value, which is a function, to two separate ...