[PHP] Använda klasser i klasser

$database = new database;
$filemanager = new file_manager; 

$filemanager->db = $database;
$filemanager->remove(...);

public function remove($id,$path,$file)
{
 //kod
}

...
else{
    global $database;
    $database->query("DELETE FROM tabellen WHERE id='$id'"); # <<---- Detta som bråkar!!
    return true;
} 
...

class db {
    private $link = db_stuff;

    public function query($sql) {
        // execute SQL qeury and return result
    }
}

class wrapper {
    private $db = new db();

    public function removeFile($id) {
        $result = $db->query("DELETE FROM tabellen WHERE id='$id'");
        return ($result == 1);
    }
}

class file_manager { 
    // har kan du anvada db istallet for wrapper som namnts tidigare!
    private $dbw = new wrapper();

    public function remove($id, $path, $file){ 
        if(!unlink($path.$file))
            return false; 
        else
            return $dbw->removeFile($id);
    }
}

A class can inherit the methods and properties of another class by using the keyword extends in the class declaration. It is not possible to extend multiple classes; a class can only inherit from one base class.

The inherited methods and properties can be overridden by redeclaring them with the same name defined in the parent class. However, if the parent class has defined a method as final, that method may not be overridden. It is possible to access the overridden methods or static properties by referencing them with parent::.

When overriding methods, the parameter signature should remain the same or PHP will generate an E_STRICT level error. This does not apply to the constructor, which allows overriding with different parameters.

<?php
class ExtendClass extends SimpleClass
{
    // Redefine the parent method
    function displayVar()
    {
        echo "Extending class\n";
        parent::displayVar();
    }
}

$extended = new ExtendClass();
$extended->displayVar();
?>