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Class/Object Functions

Introducere

These functions allow you to obtain information about classes and instance objects. You can obtain the name of the class to which an object belongs, as well as its member properties and methods. Using these functions, you can find out not only the class membership of an object, but also its parentage (i.e. what class is the object class extending).

Necesităţi

Nu sunt necesare biblioteci externe pentru a asambla această extensie.

Instalarea

Nu este necesar de a instala ceva suplimentar pentru a utiliza aceste funcţii; ele fac parte din nucleul PHP.

Configuraţia la rulare

Această extensie nu are directive de configurare definite în php.ini.

Tipurile resurselor

Această extensie nu are tipuri de resurse definite.

Constante predefinite

Această extensie nu are constante definite.

Exemple

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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