Revising php (Interace, &, Abstract, Traits and Facade

php-revision.php

<?php

    /**
     * Interface (check)
     * Abstract (check)
     * Trait (check)
     * & (check)
     * Facade (check)
     */

    interface Interace1 {}
    interface Interace2 {}
    interface Interace3 {}

    interface IAnimal extends Interace1, Interace2, Interace3{
        public function run();
    }


    class MyClass {}
    abstract class AAnimal extends MyClass {
        abstract public function eat();
        public function prey() {
            echo " I catch prey";
        }

        public function start() {
            echo "I am starting from abstract<br>";
            
        }
    }

    trait MyUseClass {
        public function start() {
            // parent::start();
            echo "I am starting from use <br>";
            
        }

        public static function stop() {
            echo "I am stopping";
        }
    }
    class Animal extends AAnimal implements IAnimal{
        use MyUseClass;
        public function eat() {
            echo "This is how i eat";
        }

        public function run() {
            echo "This is how i run";
        }
    }

    $animal = new Animal; 
    $animal->start();

    echo "<hr><hr>";

    $ar = [2,4];
    var_dump($ar);

    foreach($ar as &$val) {
        $val *= 1;
    }
    echo "<br>";

    var_dump($ar);

    echo "<hr><hr>";

    $a = 1; 
    $b = 2; 
    echo $a . $b;
    $a = &$b;
    $b = 8;
    echo $a . $b;

    echo "<hr>By reference<hr>";
    class foo {
        public $value = 42;
    
        public function &getValue() {
            return $this->value;
        }
    }
    
    $obj = new foo;
    $myValue = &$obj->getValue(); // $myValue is a reference to $obj->value, which is 42.
    $myValue = 1203;
    echo $obj->value;
    echo "<br>";
    $obj->value = 2;
    echo $myValue;