[Design Pattern in Go] Proxy

#go #design

What is Proxy pattern

A proxy, in its most general form, is a class functioning as an interface to something else. A proxy is a wrapper or agent object that is being called by the client to access the real serving object behind the scenes.

When using this pattern

The access to an object should be controlled
Additional functionality should be provided when accessing an object.

Example in Go

package main

import (
    "fmt"
)

type Car interface {
    drive()
}

type Driver struct {
   age int
}

type RealCar struct {
    driver Driver
}

func (c RealCar) drive() {
   fmt.Println("I am driving!")
}

type ProxyCar struct {
    driver Driver
    car RealCar
}

func (c ProxyCar) drive() {
   if c.driver.age < 20 {
      fmt.Println("Too young, cannot drive")
   } else {
      c.car.drive()
   }
}

func main() {
    driver := Driver{1}
    car := ProxyCar{driver, RealCar{}}
    car.drive()

    driver = Driver{40}
        car = ProxyCar{driver, RealCar{}}
    car.drive()
}

https://play.golang.org/p/SK10EKL_iXF