PHPerKaigi 2024

get_parent_class

(PHP 4, PHP 5, PHP 7, PHP 8)

get_parent_classオブジェクトの親クラスの名前を取得する

説明

get_parent_class(object|string $object_or_class = ?): string|false

オブジェクトあるいはクラスの親クラスの名前を取得します。

パラメータ

object_or_class

調べたいオブジェクトあるいはクラスの名前。

戻り値

object_or_class がインスタンスあるいは名前であるクラスの親クラス名を返します。

注意:

オブジェクトが親を持たない場合や、 指定したクラスが存在しない場合は false を返します。

変更履歴

バージョン 説明
8.3.0 get_parent_class() を引数なしでコールすると、 E_DEPRECATED が発生するようになりました。 これより前のバージョンでは、クラスの内部でこの関数をコールすると、 そのクラスの名前を返していました。
8.0.0 object_or_class は、 オブジェクトまたは有効なクラス名を受け入れるようになりました。

例1 get_parent_class() の使用例

<?php

class Dad {
function
__construct()
{
// ロジックを実装する
}
}

class
Child extends Dad {
function
__construct()
{
echo
"I'm " , get_parent_class($this) , "'s son\n";
}
}

class
Child2 extends Dad {
function
__construct()
{
echo
"I'm " , get_parent_class('child2') , "'s son too\n";
}
}

$foo = new child();
$bar = new child2();

?>

上の例の出力は以下となります。

I'm Dad's son
I'm Dad's son too

参考

  • get_class() - オブジェクトのクラス名を返す
  • is_subclass_of() - あるオブジェクトが指定したクラスのサブクラスに属するか (あるいは指定したインターフェイスを実装しているか) どうかを調べる
  • class_parents() - 与えられたクラスの親クラスを返す

add a note

User Contributed Notes 7 notes

up
6
yukal dot alexander at gmail dot com
5 years ago
An output of the entire inheritance chain using closures, recursion, and OOP

class ParentClass {
public static function getChain() {
$chain = null;
return $function = function($className='') use (& $chain, & $function) {
if (empty($className))
$className = static::class;

if (empty($chain))
$chain = $className;

$parent = get_parent_class($className);

if ($parent !== false) {
$chain .= " > {$parent}";
return $function($parent);
}

return $chain;
};
}
}

class Child extends ParentClass {}
class SubChild extends Child {}
class Sub2 extends SubChild {}
class Sub3 extends Sub2 {}
class Sub4 extends Sub3 {}
class Sub5 extends Sub4 {}
class Sub6 extends Sub5 {}
class Sub7 extends Sub6 {}

printf("%s\n", Sub7::getChain()());

$getChain = Sub7::getChain();
printf("%s\n", $getChain('Sub3'));

Output is:
Sub7 > Sub6 > Sub5 > Sub4 > Sub3 > Sub2 > SubChild > Child > ParentClass
Sub3 > Sub2 > SubChild > Child > ParentClass
up
1
jake at qzdesign dot co dot uk
4 years ago
Note that from PHP 5.5 you can also use `parent::class` from within a method, e.g.

<?php
function child()
{
echo
"I'm ", parent::class, "'s son\n";
}
?>

Looks a bit tidier and technically probably more optimal, as it avoids a function call lookup.
up
1
falundir at gmail dot com
11 years ago
You can use this function to find common parent of multiple objects or classes.

<?php
/**
* Returns name of the first (in class hierarchy) common parent class of all provided objects or classes.
* Returns FALSE when common class is not found.
*
* @param mixed $objects Array that can contain objects or class names.
* @return mixed
*/
function get_first_common_parent($objects) {
$common_ancestors = null;
foreach(
$objects as $object) {
if (
is_object($object)) {
$class_name = get_class($object);
} else {
$class_name = $object;
}

$parent_class_names = array();
$parent_class_name = $class_name;
do {
$parent_class_names[] = $parent_class_name;
} while(
$parent_class_name = get_parent_class($parent_class_name));

if (
$common_ancestors === null) {
$common_ancestors = $parent_class_names;
} else {
$common_ancestors = array_intersect($common_ancestors, $parent_class_names);
}
}

return
reset($common_ancestors);
}
?>

Example:

<?php
class A {
}

class
B extends A {
}

class
D extends B {
}

class
E extends B {
}

class
C extends A {
}

class
F extends C {
}

class
G extends F {
}

class
H {
}

//returns "A"
get_first_common_parent(array('G', 'E'));

//returns "F"
get_first_common_parent(array(new G(), 'F'));

//returns false (no common parent)
get_first_common_parent(array('C', 'H'));

//returns false (non-existent class provided)
get_first_common_parent(array(new B(), 'X'));
?>
up
1
levu
12 years ago
I wrote a simple function doing the reverse thing: get the children:

<?php
function get_child($instance, $classname) {
$class = $classname;
$t = get_class($instance);
while ((
$p = get_parent_class($t)) !== false) {
if (
$p == $class) {
return
$t;
}
$t = $p;
}
return
false;
}

abstract class
A {
function
someFunction() {
return
get_child($this, __CLASS__);
}
}

class
B extends A {

}

class
C extends B {

}

$c = new C();
echo
$c->someFunction(); //displays B

?>
up
0
ssb45 at cornell dot edu
15 years ago
"'If called without parameter outside object' What on earth does that mean?"

There are two places this could be called:
1. From within a member function of an object. In this case, it may be called with no parameters and will return the parent class of the object owning the member function. (If the parameter is included, then it will return the parent class of the specified class as normal.)

2. From outside an object (i.e., global or function scope). In this case, PHP doesn't know what class you're talking about if you don't include a parameter, so it returns FALSE. (But, of course, it works if you specify the class with the parameter.)
up
0
matt-php at DONT-SPAM-ME dot bitdifferent dot com
19 years ago
PHP (4 at least, dunno about 5) stores classnames in lower case, so:

<?PHP

class Foo
{
}

class
Bar extends Foo
{
}

echo
get_parent_class('Bar');

echo
"\n";

echo
get_parent_class('bar');

?>

will output:

foo
foo
up
0
radu dot rendec at ines dot ro
19 years ago
If the argument obj is a string and the class is not defined, then the function returns FALSE.

If the argument obj is an object created from a class with no ancestors (or a string representing a class with no ancestors), then the function returns FALSE.
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