07c06-1.php

介绍PHP5的给类型函数应用

<?php
// Define an abstract class for animals.
abstract class animal {
    // Declare variables (properties)
    public $name;

    // Make a constructor to be shared that requires a name.
    public function __construct($namesake) {
        $this->name = $namesake;
    }

    // Declare abstract methods that each animal must implement.
    abstract public function makeSound();
    abstract public function eat($what);
}

// Define a cat class
class cat extends animal {
    public function makeSound() {
        echo "Meow\n";
    }
    
    public function eat($what) {
        switch ($what) {
            case 'kibble':
            case 'cat food':
            case 'mouse':
            case 'bird':
                echo "The cat says yum!\n";
                break;
            case 'grass':
            case 'tinsel':
            case 'hair':
                echo "The cat purrs contentedly.\n";
                break;
            default:
                echo "The cat raises its head haughtily and walks off.\n";
        }
    }
}

// Define a cow class
class cow extends animal {
    public function makeSound() {
        echo "Mooooooooo!\n";
    }
    
    public function eat($what) {
        switch ($what) {
            case 'grass':
            case 'hay':
            case 'salt':
                echo "The cow chews its cud.\n";
                break;
            default:
                echo "The cow walks off ignoring it.\n";
        }
    }
}

// Declare a cat & a cow.
$my_cat = new cat('Mimi-ow');
$my_cow = new cow('Gertrude');

echo '<pre>';

// The cat says: Meow
$my_cat->makeSound();

// The cow says: Moo
$my_cow->makeSound();

// What do they each do when they eat grass?
$my_cat->eat('grass');
$my_cow->eat('grass');

echo '</pre>';
?>