is_a

Checks if the object is of this class or has this class as one of its parents (PHP 4 >= 4.2.0, PHP 5)
bool is_a ( object object, string class_name )

Example 383. is_a() example

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<?php
// define a class
class WidgetFactory
{

  var $oink = 'moo';

}

// create a new object
$WF = new WidgetFactory();


if (is_a($WF, 'WidgetFactory')) {

  echo "yes, \$WF is still a WidgetFactory\n";

}
?>

Example 384. Using the instanceof operator in PHP 5

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<?php
if ($WF instanceof WidgetFactory) {

    echo 'Yes, $WF is a WidgetFactory';

}
?>

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Code Examples / Notes » is_a

martin dunisch

Workaround for older PHP-Versions: function is_a($anObject, $aClass) { return get_class($anObject) == strtolower($aClass) or is_subclass_of($anObject, $aClass); }

dead dot screamer

Why I test if class `A` inherit class `B` or implements interface `C` before I create class `A`? <? //That isn't work: //1. function is_A() if(is_A('A','B'))$a=new A; if(is_A('A','C'))$a=new A; //2. operator instanceOf if(A instanceOf B)$a=new A; if(A instanceOf C)$a=new A; ?>

aidan

This functionality is now implemented in the PEAR package PHP_Compat. More information about using this function without upgrading your version of PHP can be found on the below link: http://pear.php.net/package/PHP_Compat

zabmilenko

Lazy Instantiation using is_a() and php5 <?php class ObjectA { public function print_line($text) { print $text . "\n"; } } class ObjectB { public function ObjectA() { static $objecta; if (!is_a('ObjectA', $objecta)) { $objecta = new ObjectA; } return $objecta; } } $obj = new ObjectB; $obj->ObjectA()->print_line('testing, 1 2 3'); ?> In the above example, ObjectA is not instantiated until needed by ObjectB. Then ObjectB can continually use it's creation as needed without reinstantiating it. There are other ways, but I like this one :-)

cesoid

is_a returns TRUE for instances of children of the class. For example: class Animal {} class Dog extends Animal {} $test = new Dog(); In this example is_a($test, "Animal") would evaluate to TRUE as well as is_a($test, "Dog"). This seemed intuitive to me, but did not seem to be documented.

zabmilenko

In the below example, the object and class name need to be reversed. Sorry. Wrong: 'ObjectA', $objecta Right: $objecta, 'ObjectA'

p dot scheit

At least in PHP 5.1.6 this works as well with Interfaces. <?php interface test { public function A(); } class TestImplementor implements test { public function A () { print "A"; } } $testImpl = new TestImplementor(); var_dump(is_a($testImpl,'test')); ?> will return true

Change Language

call_user_method_array
call_user_method
class_exists
get_class_methods
get_class_vars
get_class
get_declared_classes
get_declared_interfaces
get_object_vars
get_parent_class
interface_exists
is_a
is_subclass_of
method_exists
property_exists