is_a
This might be useful to someone, so:
If you're using Autoload, you should be aware that this will attempt to autoload $classname if it isn't already loaded. I discovered this when I had something using is_subclass_of inside an error thrown by autoload, which then recursed until it ran out of memory.
is_subclass_of
(PHP 4, PHP 5)
is_subclass_of — Checks if the object has this class as one of its parents
Descrierea
Checks if the given object has the class class_name as one of its parents.
Parametri
- object
-
A class name or an object instance
- class_name
-
The class name
Valorile întroarse
This function returns TRUE if the object object , belongs to a class which is a subclass of class_name , FALSE otherwise.
Istoria schimbărilor
| Versiunea | Descriere |
|---|---|
| 5.0.3 | You may also specify the object parameter as a string (the name of the class) |
Exemple
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";
}
?>
Exemplul de mai sus va afişa:
yes, $WFC is a subclass of WidgetFactory no, $WF is not a subclass of WidgetFactory yes, WidgetFactory_Child is a subclass of WidgetFactory
Vedeţi de asemenea
- get_class() - Returns the name of the class of an object
- get_parent_class() - Retrieves the parent class name for object or class
- is_a() - Checks if the object is of this class or has this class as one of its parents
add a note
User Contributed Notesis_subclass_of
nicholas at aquarionics dot com
17-Mar-2009 09:02
17-Mar-2009 09:02
Damien Bezborodov
17-Mar-2009 12:55
17-Mar-2009 12:55
If you need something similar to is_subclass_of() to determine if a class implements an interface before instantiating it, use reflection:
<?php
interface A_Interface {}
class A implements A_Interface {}
$reflectionA = new ReflectionClass('A');
var_dump(
$reflectionA->implementsInterface('A_Interface')
);
?>
bool(true)
kostyl_kostyl gav-gav mail point ru
07-Mar-2009 11:08
07-Mar-2009 11:08
<?php
interface I {
}
class A implements I {
}
class B extends A {
}
if (is_subclass_of('A', 'I')) {
echo 'good<br>';
}
else {
echo 'bad<br>';
}
if (is_subclass_of('B', 'I')) {
echo 'good<br>';
}
else {
echo 'bad<br>';
}
if (is_subclass_of('B', 'A')) {
echo 'good<br>';
}
else {
echo 'bad<br>';
}
?>
result:
bad <- you must to describe intermediate class B to be good
good
good
jm
01-Oct-2008 03:02
01-Oct-2008 03:02
It would appear that is_subclass_of is case insensitive unlike get_class in php5.
i.e.
<?php
class fooBar {}
class bar extends fooBar {}
assert(get_class(new fooBar()) == "fooBar");
assert(is_subclass_of(new bar(), "foobar") == true);
?>
i run across this while migrating some code from php4 to php5 and the code would only half-the-time break.
Ondra Zizka
13-Oct-2006 12:31
13-Oct-2006 12:31
For PHP4:
<?php
/** Returns whether specified class is subclass of the other class. */
function is_subclass($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');
?>
gunniboyh at web dot de
20-May-2006 01:16
20-May-2006 01:16
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 01:32
this function does not check interfaces, unlike instanceof operator.
youcantryreachingme at REMOVEME dot hotmail dot com
22-Mar-2005 02:15
22-Mar-2005 02:15
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.