Getting the name of a child class in the parent class (static context)

Question

I\'m building an ORM library with reuse and simplicity in mind; everything goes fine except that I got stuck by a stupid inheritance limitation. Please consider the code bel

Answer 1

in short. this is not possible. in php4 you could implement a terrible hack (examine the debug_backtrace()) but that method does not work in PHP5. references:

• 30423

• 37684

• 34421

edit: an example of late static binding in PHP 5.3 (mentioned in comments). note there are potential problems in it's current implementation (src).

class Base {
    public static function whoAmI() {
        return get_called_class();
    }
}

class User extends Base {}

print Base::whoAmI(); // prints "Base"
print User::whoAmI(); // prints "User"

Answer 2

Two variations on Preston's answer:

1)

class Base 
{
    public static function find($id)
    {
        $table = static::$_table;
        $class = static::$_class;
        $data = array('table' => $table, 'id' => $id);
        return new $class($data);
    }
}

class User extends Base
{
    public static $_class = 'User';
}

2)

class Base 
{
    public static function _find($class, $id)
    {
        $table = static::$_table;
        $data = array('table' => $table, 'id' => $id);
        return new $class($data);
    }
}

class User extends Base
{
    public static function find($id)
    {
        return self::_find(get_class($this), $id);
    }
}

Note: starting a property name with _ is a convention that basically means "i know i made this public, but it really should have been protected, but i couldn't do that and achieve my goal"

Answer 3

I know this question is really old, but for those looking for a more practical solution than defining a property in every class containing the class name:

You can use the static keyword for this.

As explained in this contributor note in the php documentation

the static keyword can be used inside a super class to access the sub class from which a method is called.

Example:

class Base
{
    public static function init() // Initializes a new instance of the static class
    {
        return new static();
    }

    public static function getClass() // Get static class
    {
        return static::class;
    }

    public function getStaticClass() // Non-static function to get static class
    {
        return static::class;
    }
}

class Child extends Base
{

}

$child = Child::init();         // Initializes a new instance of the Child class

                                // Output:
var_dump($child);               // object(Child)#1 (0) {}
echo $child->getStaticClass();  // Child
echo Child::getClass();         // Child

Answer 4

The problem is not a language limitation, it is your design. Never mind that you have classes; the static methods belie a procedural rather than object-oriented design. You're also using global state in some form. (How does get_row_from_db_as_array() know where to find the database?) And finally it looks very difficult to unit test.

Try something along these lines.

$db = new DatabaseConnection('dsn to database...');
$userTable = new UserTable($db);
$user = $userTable->get(24);

Answer 5

I know its old post but want to share the solution I have found.

Tested with PHP 7+ Use the function get_class()link

<?php
abstract class bar {
    public function __construct()
    {
        var_dump(get_class($this));
        var_dump(get_class());
    }
}

class foo extends bar {
}

new foo;
?>

The above example will output:

string(3) "foo"
string(3) "bar"

Answer 6

You don't need to wait for PHP 5.3 if you're able to conceive of a way to do this outside of a static context. In php 5.2.9, in a non-static method of the parent class, you can do:

get_class($this);

and it will return the name of the child class as a string.

i.e.

class Parent() {
    function __construct() {
        echo 'Parent class: ' . get_class() . "\n" . 'Child class: ' . get_class($this);
    }
}

class Child() {
    function __construct() {
        parent::construct();
    }
}

$x = new Child();

this will output:

Parent class: Parent
Child class: Child

sweet huh?