The decorator/decorator.go file

Let's look at our decorator.go implementation. It's in the 02_decorator directory, and the package name is decorator:

package decorator

import (
       "log"
       "net/http"
       "sync/atomic"
       "time"
)


type Client interface {
       Do(*http.Request) (*http.Response, error)
}

// ClientFunc is a function type that implements the client interface.
type ClientFunc func(*http.Request) (*http.Response, error)

func (f ClientFunc) Do(r *http.Request) (*http.Response, error) {
       return f(r)
}

The ClientFunc function is a function type that implements the Client interface.

We also define two additional methods that act as the getter and setter for the ratelimitDuration value:

var ratelimitDuration time.Duration

func (f ClientFunc) SetRatelimit(duration time.Duration) (error) {
       ratelimitDuration = duration
       return nil
}

func (f ClientFunc) GetRatelimit() (time.Duration, error) {
       return ratelimitDuration, nil
}

Next, we define the Decorator function type to wrap our  Client with additional behavior:

type Decorator func(Client) Client