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July 27, 2017 09:13
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Basic OOP Composition over inheritance example
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| <?php | |
| error_reporting(-1); | |
| ini_set('display_errors', true); | |
| abstract class CalculatorFactory | |
| { | |
| public static function create($string, $value) | |
| { | |
| $className = ucfirst($string) . 'Calculator'; | |
| if (!class_exists($className)) { | |
| return null; | |
| } | |
| return new $className($value); | |
| } | |
| } | |
| trait CalculatorTrait | |
| { | |
| private $newValue = 0; | |
| public function __construct($newValue) | |
| { | |
| if (!is_numeric($newValue)) { | |
| $this->newValue = 0; | |
| return; | |
| } | |
| $this->newValue = $newValue; | |
| } | |
| public function getValue() | |
| { | |
| return $this->newValue; | |
| } | |
| } | |
| class CalculatorChain | |
| { | |
| private $total = 0; | |
| private $chain = []; | |
| /** | |
| * @return int | |
| */ | |
| public function getTotal() | |
| { | |
| return $this->total; | |
| } | |
| public function add(Calculator $calculator) | |
| { | |
| $total = $calculator->calculate($this->total); | |
| if ($total !== $this->total) { | |
| $this->chain[] = $calculator; | |
| $this->total = $total; | |
| } | |
| } | |
| /** | |
| * @return Calculator[] | |
| */ | |
| public function getCalculation() | |
| { | |
| return $this->chain; | |
| } | |
| public function reset() | |
| { | |
| $this->chain = []; | |
| } | |
| } | |
| interface Calculator | |
| { | |
| public function calculate($lastValue); | |
| public function getValue(); | |
| public function getSign(); | |
| } | |
| class AddCalculator implements Calculator | |
| { | |
| use CalculatorTrait; | |
| public function calculate($lastValue) | |
| { | |
| return $lastValue + $this->newValue; | |
| } | |
| public function getSign() | |
| { | |
| return '+'; | |
| } | |
| } | |
| class SubtractCalculator implements Calculator | |
| { | |
| use CalculatorTrait; | |
| public function calculate($lastValue) | |
| { | |
| return $lastValue - $this->newValue; | |
| } | |
| public function getSign() | |
| { | |
| return '-'; | |
| } | |
| } | |
| class MultiplyCalculator implements Calculator | |
| { | |
| use CalculatorTrait; | |
| public function calculate($lastValue) | |
| { | |
| return $lastValue * $this->newValue; | |
| } | |
| public function getSign() | |
| { | |
| return '*'; | |
| } | |
| } | |
| class DivideCalculator implements Calculator | |
| { | |
| use CalculatorTrait; | |
| public function calculate($lastValue) | |
| { | |
| if (0 == $this->newValue) { | |
| return 'Cannot devide by Zero'; | |
| } | |
| return $lastValue / $this->newValue; | |
| } | |
| public function getSign() | |
| { | |
| return '/'; | |
| } | |
| } | |
| session_start(); | |
| $calculatorChain = new CalculatorChain(); | |
| if (isset($_SESSION['calculatorChain'])) { | |
| $calculatorChain = $_SESSION['calculatorChain']; | |
| } | |
| $value = 0; | |
| if (isset($_SERVER['REQUEST_METHOD']) && 'POST' === $_SERVER['REQUEST_METHOD']) { | |
| $value = $_POST['value']; | |
| $calculation = isset($_GET['calculation']) ? $_GET['calculation'] : null; | |
| $calculator = CalculatorFactory::create($calculation, $value); | |
| if ($calculator) { | |
| $calculatorChain->add($calculator); | |
| } | |
| if (isset($_GET['result'])) { | |
| $calculatorChain->reset(); | |
| $value = 0; | |
| } | |
| } | |
| $_SESSION['calculatorChain'] = $calculatorChain; | |
| header('Content-Type:text/html;charset=utf-8'); | |
| ?> | |
| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <title>Calculator</title> | |
| <meta charset="UTF-8"/> | |
| </head> | |
| <body> | |
| <fieldset> | |
| <legend>Output</legend> | |
| <div> | |
| <small><?php foreach ($calculatorChain->getCalculation() as $calculation): ?> | |
| <?= $calculation->getValue() ?> <?= $calculation->getSign() ?> | |
| <?php endforeach; ?> | |
| </small> | |
| <div><?= $calculatorChain->getTotal() ?></div> | |
| </div> | |
| </fieldset> | |
| <fieldset> | |
| <legend>Calculator</legend> | |
| <form method="POST"> | |
| <label> | |
| Value: <input name="value" value="<?= $value ?>"/> | |
| </label> | |
| <button name="action" formaction="?calculation=add">+</button> | |
| <button name="action" formaction="?calculation=subtract">-</button> | |
| <button name="action" formaction="?calculation=multiply">*</button> | |
| <button name="action" formaction="?calculation=divide">/</button> | |
| <button name="action" formaction="?result">=</button> | |
| </form> | |
| </fieldset> | |
| </body> | |
| </html> |
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