Lista de Palabras Reservadas
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.
Lista de Palabras Clave
Estas palabras tienen un significado especial en PHP. Algunas representan cosas que parecen funciones, otras parecen a constantes, etc --pero no lo son, en realidad: son constructores del lenguaje. No se puede usar ninguna de las siguientes palabras en constantes, nombres de clases, nombres de funciones o métodos. Se pueden usar como nombres de variables, pero puede dar lugar a confusiones.
| abstract (disponible desde PHP 5) | and | array() | as | break |
| case | catch (disponible desde PHP 5) | cfunction (sólo en PHP 4) | class | clone (disponible desde PHP 5) |
| const | continue | declare | default | do |
| else | elseif | enddeclare | endfor | endforeach |
| endif | endswitch | endwhile | extends | final (disponible desde PHP 5) |
| for | foreach | function | global | goto (disponible desde PHP 5.3) |
| if | implements (disponible desde PHP 5) | interface (disponible desde PHP 5) | instanceof (disponible desde PHP 5) | |
| namespace (disponible desde PHP 5.3) | new | old_function (sólo en PHP 4) | or | private (disponible desde PHP 5) |
| protected (disponible desde PHP 5) | public (disponible desde PHP 5) | static | switch | throw (disponible desde PHP 5) |
| try (disponible desde PHP 5) | use | var | while | xor |
| __CLASS__ | __DIR__ (disponible desde PHP 5.3) | __FILE__ | __LINE__ | __FUNCTION__ | __METHOD__ |
| __NAMESPACE__ (disponible desde PHP 5.3) |
| die() | echo | empty() | exit() | eval() |
| include | include_once | isset() | list() | require |
| require_once | return | unset() | __halt_compiler() |
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User Contributed Notes
Lista de Palabras Clave
Bob
06-Sep-2009 02:02