Liste der reservierten Wörter
There are some cases when you need to use a reserved keyword or language construct as a class method name. In this instance, there is very little chance of namespace conflicts (as the class itself acts as a namespace). If you try to define the method the old way, you will get an unexpected token error.
There is an unobtrusive, and very useful way to use a reserved keyword for a method name. For example, you want to define two class methods 'list' and 'unset' (these two are language builtins and normally not allowed for method names).
<?php
class MyClass
{
// Define MyClass::unset() with a different name, e.g. 'rm'
public function rm($arg)
{
/* code... */
}
// Define MyClass::list() with a different name, e.g. 'ls'
public function ls($arg = null)
{
/* code... */
}
// Now define a __call() method (requires PHP > 5.2.3 to take effect)
public function __call($func, $args)
{
switch ($func)
{
case 'list':
return $this->ls((isset($args[0]))? $args[0]: null);
break;
case 'unset':
return $this->rm($args[0]);
break;
default:
trigger_error("Call to undefined method ".__CLASS__."::$func()", E_USER_ERROR);
die ();
}
}
}
?>
The only caveat is that to use the long method names, you need PHP > 5.2.3. However, a nice feature is that if you are using an older version than 5.2.3, all of the __call() stuff is ignored and the class will behave as expected (in other words, it degrades gracefully).
You also need to be aware of the methods' expected arguments. MyClass::ls()'s argument is optional, so the extra isset() check is required. If your methods take more arguments, they will need to be manually dereferenced from the $args array, e.g. <?php return $this->my_func($args[0], $args[1], $args[2]);?> for 3 required arguments.
This is a nice trick, and can let you code better APIs for newer versions of PHP. However, if this script is to be run on older PHP installations, be very sure to use the short method names.
Liste der Schlüsselworte
Die folgenden Begriffe haben in PHP eine spezielle Bedeutung. Einige von ihnen sehen aus wie Funktionen, Konstanten usw., in Wirklichkeit handelt es sich aber um Sprachkonstrukte. Keines der folgenden Worte kann als Name für eine benutzerdefinierte Konstante, Klasse, Funktion oder Methode genutzt werden. Die Nutzung als Variablenname ist in der Regel möglich, sollte aber unterlassen werden um Verwirrung zu vermeiden.
| abstract (ab PHP 5) | and | array() | as | break |
| case | catch (ab PHP 5) | cfunction (nur PHP 4) | class | clone (ab PHP 5) |
| const | continue | declare | default | do |
| else | elseif | enddeclare | endfor | endforeach |
| endif | endswitch | endwhile | extends | final (ab PHP 5) |
| for | foreach | function | global | goto (ab PHP 5.3) |
| if | implements (ab PHP 5) | interface (ab PHP 5) | instanceof (ab PHP 5) | |
| namespace (ab PHP 5.3) | new | old_function (nur PHP 4) | or | private (ab PHP 5) |
| protected (ab PHP 5) | public (ab PHP 5) | static | switch | throw (ab PHP 5) |
| try (ab PHP 5) | use | var | while | xor |
| __CLASS__ | __DIR__ (ab PHP 5.3) | __FILE__ | __FUNCTION__ | __METHOD__ |
| __NAMESPACE__ (ab PHP 5.3) |
| die() | echo() | empty() | exit() | eval() |
| include() | include_once() | isset() | list() | require() |
| require_once() | return() | print() | unset() |
add a note
User Contributed NotesListe der Schlüsselworte
Bob
06-Sep-2009 11:02
06-Sep-2009 11:02