Building RESTful Web services with Go

Creating a basic middleware

Building middleware is simple and straightforward. Let us build a program based on the knowledge gained from the second chapter. If you are not familiar with closure functions, a closure function returns another function. This principle helps us write middleware. The first thing we should do is implement a function that satisfies the http.Handler interface.

A sample closure called closure.go looks like this:

package mainimport (    "fmt")func main() {    numGenerator := generator()    for i := 0; i < 5; i++ {        fmt.Print(numGenerator(), "\t")    }}// This function returns another functionfunc generator() func() int {    var i = 0    return func() int {        i++        return i    }}

If we run this code:

go run closure.go

Numbers will be generated ...