予約語の一覧
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.
キーワードのリスト
これらのキーワードは、PHP では特別な意味があります。これらのいくつかは 関数やメソッドのようなものを表し、いくつかは定数のようなものを表す、 といったようになっていますが、実際にはそうではありません。実際には、 これらは言語を構成するものです。以下のキーワードはいずれも定数、クラス名、 関数名として使用することはできません。 これらを変数名として使用することは一般的には可能ですが、 混乱を生じる可能性があります。
| abstract (PHP 5 以降) | and | array() | as | break |
| case | catch (PHP 5 以降) | cfunction (PHP 4 のみ) | class | clone (PHP 5 以降) |
| const | continue | declare | default | do |
| else | elseif | enddeclare | endfor | endforeach |
| endif | endswitch | endwhile | extends | final (PHP 5 以降) |
| for | foreach | function | global | goto (PHP 5.3 以降) |
| if | implements (PHP 5 以降) | interface (PHP 5 以降) | instanceof (PHP 5 以降) | |
| namespace (PHP 5.3 以降) | new | old_function (PHP 4 のみ) | or | private (PHP 5 以降) |
| protected (PHP 5 以降) | public (PHP 5 以降) | static | switch | throw (PHP 5 以降) |
| try (PHP 5 以降) | use | var | while | xor |
| __CLASS__ | __DIR__ (PHP 5.3 以降) | __FILE__ | __FUNCTION__ | __METHOD__ |
| __NAMESPACE__ (PHP 5.3 以降) |
| die() | echo() | empty() | exit() | eval() |
| include() | include_once() | isset() | list() | require() |
| require_once() | return() | print() | unset() |
add a note
User Contributed Notesキーワードのリスト
Bob
06-Sep-2009 09:02
06-Sep-2009 09:02