javascript / PHP [Design Patterns - Facade Pattern]

This pattern involves a single class which provides simplified methods required by client and delegates calls to methods of existing system classes.

 

/**
 * Design Patterns - Facade Pattern
 * https://www.tutorialspoint.com/design_pattern/facade_pattern.htm
 */
// interface
function Shape() {}
Shape.prototype.draw = function() {throw "Shape::draw() must be overridden";};

// implements Shape
function Rectangle() {
    Shape.call(this);
}
Rectangle.prototype = new Shape();
Rectangle.prototype.draw = function() {
    console.log("Rectangle::draw()");
};

// implements Shape
function Square() {
    Shape.call(this);
}
Square.prototype = new Shape();
Square.prototype.draw = function() {
    console.log("Square::draw()");
};

// implements shape
function Circle() {
    Shape.call(this);
}
Circle.prototype = new Shape();
Circle.prototype.draw = function() {
    console.log("Circle::draw()");
};

function ShapeMaker() {
    this.circle = new Circle();
    this.rectangle = new Rectangle();
    this.square = new Square();
}
ShapeMaker.prototype.drawCircle = function() {
    this.circle.draw();
};
ShapeMaker.prototype.drawRectangle = function() {
    this.rectangle.draw();
};
ShapeMaker.prototype.drawSquare = function() {
    this.square.draw();
};

function FacadePatternDemo() {
    this.shapeMaker = new ShapeMaker();
}
FacadePatternDemo.prototype.main = function() {
    this.shapeMaker.drawCircle();
    this.shapeMaker.drawRectangle();
    this.shapeMaker.drawSquare();
};

var demo = new FacadePatternDemo();
demo.main();

　　

Output:

Circle::draw()
Rectangle::draw()
Square::draw()

 

<?php
/**
 * The complicated, underlying logic.
 */
class CPU {
    public function freeze() {
        echo 'CPU freeze'.PHP_EOL;
    }
    public function jump($position) {
        printf("CPU jumping to 0x%x %s", $position, PHP_EOL);
    }
    public function execute() {
        echo 'CPU executing...'.PHP_EOL;
    }
}

class Memory {
    public function load($position, $data) {
        printf("Loading position 0x%x from memory, \"%s\"%s", $position, implode('', $data), PHP_EOL);
    }
}

class HardDrive
{
    public function read($lba, $size) {
        printf("HardDrive is reading sector#%d, size=%d %s", $lba, $size, PHP_EOL);
        return ['H','e','l','l','o'];
    }
}

/**
 * The facade that users would be interacting with.
 */
class ComputerFacade
{
    protected $cpu;
    protected $memory;
    protected $hd;

    public function __construct()
    {
        $this->cpu = new CPU;
        $this->ram = new Memory;
        $this->hd = new HardDrive;
    }

    public function start()
    {
        $this->cpu->freeze();
        $this->ram->load(0x8280, $this->hd->read(0, 512));
        $this->cpu->jump(0x8280);
        $this->cpu->execute();
    }
}

/**
 * How a user could start the computer.
 */
$computer = new ComputerFacade;
$computer->start();

　　

OUTPUT:

CPU freeze
HardDrive is reading sector#0, size=512
Loading position 0x8280 from memory, "Hello"
CPU jumping to 0x8280
CPU executing...