PHP 7.4.0 alpha 1 Released

is_subclass_of

(PHP 4, PHP 5, PHP 7)

is_subclass_of이 클래스가 부모 클래스의 자식인지 확인

설명

bool is_subclass_of ( mixed $object , string $class_name )

주어진 object의 부모 중에 class_name 클래스가 존재하는지 확인합니다.

인수

object

클래스명이나 객체 인스턴스

class_name

클래스명

반환값

objectclass_name의 자식 클래스면 TRUE, 아니면 FALSE를 반환합니다.

변경점

버전 설명
5.0.3 object 인수를 문자열(클래스명)로 지정할 수 있습니다.

예제

Example #1 is_subclass_of() 예제

<?php
// 클래스 정의
class WidgetFactory
{
  var 
$oink 'moo';
}

// 자식 클래스 정의
class WidgetFactory_Child extends WidgetFactory
{
  var 
$oink 'oink';
}

// 새 객체 생성
$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";
}


// PHP 5.3.0부터 사용 가능
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";
}
?>

위 예제의 출력:

yes, $WFC is a subclass of WidgetFactory
no, $WF is not a subclass of WidgetFactory
yes, WidgetFactory_Child is a subclass of WidgetFactory

참고

  • get_class() - 객체의 클래스명을 반환
  • get_parent_class() - 객체나 클래스의 부모 클래스명을 얻습니다
  • is_a() - 객체가 이 클래스나 부모 클래스 중 하나인지 확인

add a note add a note

User Contributed Notes 7 notes

up
9
gunniboyh at web dot de
13 years ago
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' .
up
6
nicholas at aquarionics dot com
10 years ago
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.
up
0
alan at jynxy.net
11 months ago
The $allow_string parameter is not very clearly documented. When true, it simply allows the first parameter to be the name of a class, instead of an object whose class we are interested in.

Some usage examples:

class parent_class {
    // objects and methods ...
}

$possible_child_object = new possible_child_class(); // might be an extension of parent_class

$result = is_subclass_of($possible_child_object, 'parent_class'); //  valid
$result = is_subclass_of($possible_child_object, 'parent_class', false); //  valid
$result = is_subclass_of('possible_child_class', 'parent_class', true); // valid
$result = is_subclass_of('possible_child_class', 'parent_class', false); // not valid
up
0
jm
10 years ago
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.
up
-1
Damien Bezborodov
10 years ago
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)
up
-3
Ondra Zizka
12 years ago
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');
?>
up
-5
kostyl_kostyl gav-gav mail point ru
10 years ago
<?php
interface I {
}
class
A implements I {
}
class
B extends {
}
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
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