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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 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

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