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 or not 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 classes.inc


<?php



// base class with member properties and methods

class Vegetable {



   var $edible;

   var $color;



   function Vegetable($edible, $color="green") 

   {

       $this->edible = $edible;

       $this->color = $color;

   }



   function is_edible() 

   {

       return $this->edible;

   }



   function what_color() 

   {

       return $this->color;

   }

   

} // end of class Vegetable



// extends the base class

class Spinach extends Vegetable {



   var $cooked = false;



   function Spinach() 

   {

       $this->Vegetable(true, "green");

   }



   function cook_it() 

   {

       $this->cooked = true;

   }



   function is_cooked() 

   {

       return $this->cooked;

   }

   

} // end of class Spinach



?>

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


<pre>

<?php



include "classes.inc";



// utility functions



function print_vars($obj) 

{

foreach (get_object_vars($obj) as $prop => $val) {

    echo "\t$prop = $val\n";

}

}



function print_methods($obj) 

{

$arr = get_class_methods(get_class($obj));

foreach ($arr as $method) {

    echo "\tfunction $method()\n";

}

}



function class_parentage($obj, $class) 

{

if (is_subclass_of($GLOBALS[$obj], $class)) {

    echo "Object $obj belongs to class " . get_class($$obj);

    echo " a subclass of $class\n";

} else {

    echo "Object $obj 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";

print_vars($veggie);



// and leafy methods

echo "\nleafy: Methods\n";

print_methods($leafy);



echo "\nParentage:\n";

class_parentage("leafy", "Spinach");

class_parentage("leafy", "Vegetable");

?>

</pre>

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, therefore the last part of the script above will output:

   [...]
Parentage:
Object leafy does not belong to a subclass of Spinach
Object leafy belongs to class spinach a subclass of Vegetable