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Examples

In this example, we first define a base class and an extension of the class. The base class describes a general vegetable, whether it is edible, and what is its color. The subclass Spinach adds a method to cook it and another to find out if it is cooked.

Example #1 Class Definitions

Vegetable

<?php

class Vegetable {
public
$edible;

public
$color;

public function
__construct($edible, $color = "green")
{
$this->edible = $edible;
$this->color = $color;
}

public function
isEdible()
{
return
$this->edible;
}

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

?>

Spinach

<?php

class Spinach extends Vegetable {
public
$cooked = false;

public function
__construct()
{
parent::__construct(true, "green");
}

public function
cook()
{
$this->cooked = true;
}

public function
isCooked()
{
return
$this->cooked;
}
}

?>

We then instantiate 2 objects from these classes and print out information about them, including their class parentage. We also define some utility functions, mainly to have a nice printout of the variables.

Example #2 test_script.php

<?php

// register autoloader to load classes
spl_autoload_register();

function
printProperties($obj)
{
foreach (
get_object_vars($obj) as $prop => $val) {
echo
"\t$prop = $val\n";
}
}

function
printMethods($obj)
{
$arr = get_class_methods(get_class($obj));
foreach (
$arr as $method) {
echo
"\tfunction $method()\n";
}
}

function
objectBelongsTo($obj, $class)
{
if (
is_subclass_of($obj, $class)) {
echo
"Object belongs to class " . get_class($obj);
echo
", a subclass of $class\n";
} else {
echo
"Object does not belong to a subclass of $class\n";
}
}

// instantiate 2 objects
$veggie = new Vegetable(true, "blue");
$leafy = new Spinach();

// print out information about objects
echo "veggie: CLASS " . get_class($veggie) . "\n";
echo
"leafy: CLASS " . get_class($leafy);
echo
", PARENT " . get_parent_class($leafy) . "\n";

// show veggie properties
echo "\nveggie: Properties\n";
printProperties($veggie);

// and leafy methods
echo "\nleafy: Methods\n";
printMethods($leafy);

echo
"\nParentage:\n";
objectBelongsTo($leafy, Spinach::class);
objectBelongsTo($leafy, Vegetable::class);

?>

The above examples will output:

veggie: CLASS Vegetable
leafy: CLASS Spinach, PARENT Vegetable

veggie: Properties
        edible = 1
        color = blue

leafy: Methods
        function __construct()
        function cook()
        function isCooked()
        function isEdible()
        function getColor()

Parentage:
Object does not belong to a subclass of Spinach
Object belongs to class Spinach, a subclass of Vegetable

One important thing to note in the example above is that the object $leafy is an instance of the class Spinach which is a subclass of Vegetable.

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