How does ServeHTTP work?

Question

I am studying web development in Golang (Beginner) I came across some code I played around with and I\'m not too sure why it works, I looked through the library source code

Answer 1

Type declaration in this code for

type foo int

is implementing Handler interface. We can create struct or any type to implement ServeHTTP method. like

type Foo struct{}
func (m foo) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "Some text")
}

For implementing Handler interface or any other interface It is been required to implement all methods declared in the interface on a type which is foo here.

HandlerFunc is implementing ServeHttp method of Handler interface and hence can be passed to http.ListenAndServe as a handler. It can be used to create middlewares wrapping around ServeHttp.

For more information on HanlderFunc use go doc in terminal

godoc net/http HanlderFunc