Object dependencies, member variables (homework example)

I'm in the process of creating a wool farm, where sheep are sheared in the machine if they are old. The wool is counted by the color, there is black and white.

Each mentioned attribute is random:

• Age: Young = 0, Old = 1
• Color (Black, White).

I understand the logic, but I don't know how to send groups of sheep to the machine, and I can't make the counter to increase if I make more sheep. (During the assignation I was asked to do this).

I commented the code for further understanding: http://gabrielmeono.com/theFarm.zip

<?php 
class Sheep{
    //Atributes
    const COLOR_WHITE = 'white';
    const COLOR_BLACK = 'black';
    const AGE_YOUNG = 0;
    const AGE_OLD = 1;

    private $_color;
    private $_age;

    //Random age and color
    public static function makeRandom(){
    if(rand(0, 1)){
        $color = self::COLOR_WHITE;
    }else{
        $color = self::COLOR_BLACK;
    }
        $age = rand(0, 1);
        return new self($color, $age);
    }

    public function __construct($color, $age){
        $this->_color = $color;
        $this->_age = $age;
    }
    //To check if the sheep was created and had all the atributes.
    public function report(){
        echo '<br>This sheep is '.$this->_color.' and '.$this->_age.'<br/>';//Old age is 1. 

        }

}


class machine {
    //The machine should shear wool only if the sheep is old. Old equals 1.
    public function Shear($collector){
        switch($collector)
        {
            case $sheep->_age = 1;
                echo 'Sheep sheared <br/>';
            break;
            default:
                echo 'This sheep is not ready to be sheared <br/>';
            break;

        }
    }
    //Here I should be able to count and separate wool by color.
    public function Counter($whiteWool, $blackWool, $count){ //This is my notion how it should start...Correct me if I'm wrong.


        }
    }

$sheep = Sheep::makeRandom();
$sheep -> report();
$machine = new machine ();
$machine -> Shear(0);
//I don't know how to connect 开发者_运维百科the machine class with the sheep class.
//Batch creation and processing of sheep is beyond my understanding.
?>

As others have said, you can add the sheep to the machine through injection. The shear method actually makes the most sense to me.

public function Shear(Sheep $sheep) {
   switch ($sheep->age) {} // etc.
}

In fact, I would take this a step further by having the sheep react to the shearing.

public static function makeRandom() {
   // ...
   return new $age ? OldSheep($color) : YoungSheep($color);
}

Or even better:

private static $ages = array(0 => 'Old', 1 => 'Young')
public static function makeRandom() {
   // ...
   $sheepclass = $ages[$age] . 'Sheep';
   return new $sheepclass($color);
}

Then when it's time for shearing:

interface Sheepable {
   function prepareToShear(machine $mach);
}

class OldSheep implements Sheepable {
   public function prepareToShear(machine $mach) {
      echo "Sheep is ready to be shorn";
      $mach->shear($this);
   }
}

class YoungSheep implements Sheepable {
   public function prepareToShear(machine $mach) {
      echo "Sheep is not ready to be shorn";
   }
}

class machine {
   //... etc.
   public function Shear(Sheepable $sheep) {
      $sheep->prepareToShear($this);
   }
}

By the way, asking for help with homework tends to get a negative response around here.

You can inject the Sheep object to the Machine by using dependency injection (todo: google for it).

e.g.

$machine->addSheep($sheep);

addSheep method should save the $sheep object in the class member variable. Other methods may use this variable later.

You can just send $sheep (the object you created) as an argument to a function in the machine class.

I hate farming.
Don't just copypasta. Read through it, ask questions (but not duplicates) and we'll be able to assist.

interface Animal{
    const AGE_YOUNG = 0;
    const AGE_OLD = 1;
    const COLOR_WHITE = 'white';
    const COLOR_BLACK = 'black';
    public function getAge();
    public function getColor();
}

interface Shearable extends Animal{
    public function shear();
    public function isSheared();
}

class Gorilla implements Shearable{
    // ♫ seeeeeee my vest, see my vest, made of real gorilla chest ♫
}

class Sheep implements Shearable{

    private $_isSheared = false;
    private $_age = null;
    private $_color = null;

    public static function create(){
        $age = rand(0, 1);
        $color = rand(0, 1)
            ? self::COLOR_WHITE
            : self::COLOR_BLACK;
        return new self($age, $color);
    }

    public function __construct($age, $color){
        $this->_age = $age;
        $this->_color = $color;
    }

    public function shear(){
        $this->_isSheared = true;
        return $this;
    }

    public function isSheared(){
        return $this->_isSheared;
    }

    public function getAge(){
        return $this->_age;
    }

    public function getColor(){
        return $this->_color;
    }

}

class Machine{

    private $_wool = array();

    public function shearLine(Array $line){
        $unshearable = array();
        foreach($line as $animal){
            if($this->shear($animal) !== true){
                $unshearable[] = $animal;
            }
        }
        return $unshearable;
    }

    public function shear(Shearable $animal){
        if(!$animal->isSheared() && $animal->getAge() == Shearable::AGE_OLD){
            $this->_wool[] = $animal->shear()->getColor();
            return true;
        }
        return $animal;
    }

    public function getWool(){
        return count($this->_wool);
    }

    public function getWoolByColor($color){
        return count(array_keys($this->_wool, $color));
    }

}

// build a machine
$machine = new Machine();

// brew up some sheep
$lineOfSheep = array();
for($i = 0; $i < 200; $i++){
    $lineOfSheep[] = Sheep::create();
}

//make some underwear
$unshearable = $machine->shearLine($lineOfSheep);

// see how many sheep still need water and sunlight
var_dump(count($unshearable));

// see how much and of what color your underwear will be
var_dump($machine->getWool(), $machine->getWoolByColor(Shearable::COLOR_WHITE));