is_a
For PHP4:
/** Returns whether specified class is subclass of the other class. */
function is_subclass($sClass, $sExpectedParentClass){
do if( $sExpectedParentClass === $sClass ) return true;
while( false != ($sClass = get_parent_class($sClass)) );
return false;
}
// Test:
class A {} class B extends A {} class C extends B {} echo (int) is_subclass('C', 'A');
is_subclass_of
(PHP 4, PHP 5)
is_subclass_of — Checks if the object has this class as one of its parents
Description
Checks if the given object has the class class_name as one of its parents.
Parameters
- object
-
A class name or an object instance
- class_name
-
The class name
Return Values
This function returns TRUE if the object object , belongs to a class which is a subclass of class_name , FALSE otherwise.
ChangeLog
| Version | Description |
|---|---|
| 5.0.3 | You may also specify the object parameter as a string (the name of the class) |
Examples
Example #1 is_subclass_of() example
<?php
// define a class
class WidgetFactory
{
var $oink = 'moo';
}
// define a child class
class WidgetFactory_Child extends WidgetFactory
{
var $oink = 'oink';
}
// create a new object
$WF = new WidgetFactory();
$WFC = new WidgetFactory_Child();
if (is_subclass_of($WFC, 'WidgetFactory')) {
echo "yes, \$WFC is a subclass of WidgetFactory\n";
} else {
echo "no, \$WFC is not a subclass of WidgetFactory\n";
}
if (is_subclass_of($WF, 'WidgetFactory')) {
echo "yes, \$WF is a subclass of WidgetFactory\n";
} else {
echo "no, \$WF is not a subclass of WidgetFactory\n";
}
// usable only since PHP 5.0.3
if (is_subclass_of('WidgetFactory_Child', 'WidgetFactory')) {
echo "yes, WidgetFactory_Child is a subclass of WidgetFactory\n";
} else {
echo "no, WidgetFactory_Child is not a subclass of WidgetFactory\n";
}
?>
The above example will output:
yes, $WFC is a subclass of WidgetFactory no, $WF is not a subclass of WidgetFactory yes, WidgetFactory_Child is a subclass of WidgetFactory
add a note
User Contributed Notesis_subclass_of
Ondra Zizka
13-Oct-2006 03:31
13-Oct-2006 03:31
gunniboyh at web dot de
20-May-2006 04:16
20-May-2006 04:16
is_subclass_of() works also with classes between the class of obj and the superclass.
example:
<?php
class A {};
class B extends A {};
class C extends B {};
$foo=new C();
echo ((is_subclass_of($foo,'A')) ? 'true' : 'false');
?>
echoes 'true' .
01-Oct-2005 04:32
this function does not check interfaces, unlike instanceof operator.
youcantryreachingme at REMOVEME dot hotmail dot com
22-Mar-2005 04:15
22-Mar-2005 04:15
A bug report at http://pear.php.net/bugs/bug.php?id=2975 indicates that the "is_subclass_of" function can return the error message:
Warning: Unknown class passed as parameter
in the event that the class represented by the second argument hasn't yet been instantiated.