SunshinePHP Developer Conference 2015

Lista de palabras reservadas

Estas palabras tienen un significado especial en PHP. Algunas representan cosas que se parecen a funciones, otras se parecen a constantes, etc.; pero no lo son en realidad: son constructores del lenguaje. No se puede usar ninguna de las siguientes palabras como constantes, nombres de clases, nombres de funciones o métodos. Se pueden usar como nombres de variables, pero podría dar lugar a confusiones.

Palabras reservadas de PHP
__halt_compiler() abstract and array() as
break callable (a partir de PHP 5.4) case catch class
clone const continue declare default
die() do echo else elseif
empty() enddeclare endfor endforeach endif
endswitch endwhile eval() exit() extends
final finally (a partir de PHP 5.5) for foreach function
global goto (a partir de PHP 5.3) if implements include
include_once instanceof insteadof (a partir de PHP 5.4) interface isset()
list() namespace (a partir de PHP 5.3) new or print
private protected public require require_once
return static switch throw trait (a partir de PHP 5.4)
try unset() use var while
xor yield (a partir de PHP 5.5)
Constantes en tiempo de compilación
__CLASS__ __DIR__ (a partir de PHP 5.3) __FILE__ __FUNCTION__ __LINE__ __METHOD__
__NAMESPACE__ (a partir de PHP 5.3) __TRAIT__ (a partir de PHP 5.4)
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User Contributed Notes 3 notes

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16
martindilling at gmail dot com
1 year ago
RegEx to find all the keywords:

\b(
(a(bstract|nd|rray|s))|
(c(a(llable|se|tch)|l(ass|one)|on(st|tinue)))|
(d(e(clare|fault)|ie|o))|
(e(cho|lse(if)?|mpty|nd(declare|for(each)?|if|switch|while)|val|x(it|tends)))|
(f(inal|or(each)?|unction))|
(g(lobal|oto))|
(i(f|mplements|n(clude(_once)?|st(anceof|eadof)|terface)|sset))|
(n(amespace|ew))|
(p(r(i(nt|vate)|otected)|ublic))|
(re(quire(_once)?|turn))|
(s(tatic|witch))|
(t(hrow|r(ait|y)))|
(u(nset|se))|
(__halt_compiler|break|list|(x)?or|var|while)
)\b
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15
Chris
2 years ago
Here they are as arrays:

<?php
$keywords
= array('__halt_compiler', 'abstract', 'and', 'array', 'as', 'break', 'callable', 'case', 'catch', 'class', 'clone', 'const', 'continue', 'declare', 'default', 'die', 'do', 'echo', 'else', 'elseif', 'empty', 'enddeclare', 'endfor', 'endforeach', 'endif', 'endswitch', 'endwhile', 'eval', 'exit', 'extends', 'final', 'for', 'foreach', 'function', 'global', 'goto', 'if', 'implements', 'include', 'include_once', 'instanceof', 'insteadof', 'interface', 'isset', 'list', 'namespace', 'new', 'or', 'print', 'private', 'protected', 'public', 'require', 'require_once', 'return', 'static', 'switch', 'throw', 'trait', 'try', 'unset', 'use', 'var', 'while', 'xor');

$predefined_constants = array('__CLASS__', '__DIR__', '__FILE__', '__FUNCTION__', '__LINE__', '__METHOD__', '__NAMESPACE__', '__TRAIT__');
?>

Along with get_defined_functions() and get_defined_constants(), this can be useful for checking eval() statements.
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0
Bob
5 years ago
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.
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