IX. Class/Object Functions

範例

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.

範例 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.

範例 2. test_script.php

 pre 
 ?php

include "classes.inc";

// utility functions

function print_vars($obj) {
    $arr = get_object_vars($obj);
    while (list($prop, $val) = each($arr))
        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) {
    global $$obj;
    if (is_subclass_of($$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


內容目錄
call_user_method_array -- Call a user method given with an array of parameters [deprecated]
call_user_method -- Call a user method on an specific object [deprecated]
class_exists -- Checks if the class has been defined
get_class_methods -- Returns an array of class methods' names
get_class_vars -- Returns an array of default properties of the class
get_class -- Returns the name of the class of an object
get_declared_classes -- Returns an array with the name of the defined classes
get_object_vars -- Returns an associative array of object properties
get_parent_class -- Retrieves the parent class name for object or class
is_a -- Returns TRUE if the object is of this class or has this class as one of its parents
is_subclass_of -- Returns TRUE if the object has this class as one of its parents
method_exists -- Checks if the class method exists