note 106368 modified in function.get-class by danbrown
| From: | danbrown@php.net | Date: | Fri, 04 Nov 2011 14:00:55 +0000 |
| Subject: | note 106368 modified in function.get-class by danbrown | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-184302@lists.php.net to get a copy of this message | ||
Attempting various singleton base class methods described on this page, I have created a base class
and bridge function that allows it to work without get_called_class() if it's not available.
Unlike other methods listed here, I chose not to prevent use of __construct() or __clone().
<?php
abstract class Singleton {
protected static $m_pInstance;
final public static function getInstance(){
$class = static::getClass();
if(!isset(static::$m_pInstance[$class])) {
static::$m_pInstance[$class] = new $class;
}
return static::$m_pInstance[$class];
}
final public static function getClass(){
return get_called_class();
}
}
// I don't remember where I found this, but this is to allow php < 5.3 to use this method.
if (!function_exists('get_called_class')) {
function get_called_class($bt = false, $l = 1) {
if (!$bt)
$bt = debug_backtrace();
if (!isset($bt[$l]))
throw new Exception("Cannot find called class -> stack level too deep.");
if (!isset($bt[$l]['type'])) {
throw new Exception('type not set');
}
else
switch ($bt[$l]['type']) {
case '::':
$lines = file($bt[$l]['file']);
$i = 0;
$callerLine = '';
do {
$i++;
$callerLine = $lines[$bt[$l]['line'] - $i] . $callerLine;
} while (stripos($callerLine, $bt[$l]['function']) === false);
preg_match('/([a-zA-Z0-9\_]+)::' . $bt[$l]['function'] .
'/', $callerLine, $matches);
if (!isset($matches[1])) {
// must be an edge case.
throw new Exception("Could not find caller class: originating method
call is obscured.");
}
switch ($matches[1]) {
case 'self':
case 'parent':
return get_called_class($bt, $l + 1);
default:
return $matches[1];
}
// won't get here.
case '->': switch ($bt[$l]['function']) {
case '__get':
// edge case -> get class of calling object
if (!is_object($bt[$l]['object']))
throw new Exception("Edge case fail. __get called on non
object.");
return get_class($bt[$l]['object']);
default: return $bt[$l]['class'];
}
default: throw new Exception("Unknown backtrace method type");
}
}
}
class B extends Singleton {
}
class C extends Singleton {
}
$b = B::getInstance();
echo 'class: '.get_class($b);
echo '<br />';
$c = C::getInstance();
echo echo 'class: '.get_class($c);
?>
This returns:
class: b
class: c
--was--
Attempting various singleton base class methods described on this page, I have created a base class
and bridge function that allows it to work without get_called_class() if it's not available.
Unlike other methods listed here, I chose not to prevent use of __construct() or __clone().
<?php
abstract class Singleton {
protected static $m_pInstance;
final public static function getInstance(){
$class = static::getClass();
if(!static::$m_pInstance[$class]) {
static::$m_pInstance[$class] = new $class;
}
return static::$m_pInstance[$class];
}
final public static function getClass(){
return get_called_class();
}
}
// I don't remember where I found this, but this is to allow php < 5.3 to use this method.
if (!function_exists('get_called_class')) {
function get_called_class($bt = false, $l = 1) {
if (!$bt)
$bt = debug_backtrace();
if (!isset($bt[$l]))
throw new Exception("Cannot find called class -> stack level too deep.");
if (!isset($bt[$l]['type'])) {
throw new Exception('type not set');
}
else
switch ($bt[$l]['type']) {
case '::':
$lines = file($bt[$l]['file']);
$i = 0;
$callerLine = '';
do {
$i++;
$callerLine = $lines[$bt[$l]['line'] - $i] . $callerLine;
} while (stripos($callerLine, $bt[$l]['function']) === false);
preg_match('/([a-zA-Z0-9\_]+)::' . $bt[$l]['function'] .
'/', $callerLine, $matches);
if (!isset($matches[1])) {
// must be an edge case.
throw new Exception("Could not find caller class: originating method
call is obscured.");
}
switch ($matches[1]) {
case 'self':
case 'parent':
return get_called_class($bt, $l + 1);
default:
return $matches[1];
}
// won't get here.
case '->': switch ($bt[$l]['function']) {
case '__get':
// edge case -> get class of calling object
if (!is_object($bt[$l]['object']))
throw new Exception("Edge case fail. __get called on non
object.");
return get_class($bt[$l]['object']);
default: return $bt[$l]['class'];
}
default: throw new Exception("Unknown backtrace method type");
}
}
}
class B extends Singleton {
}
class C extends Singleton {
}
$b = B::getInstance();
echo 'class: '.get_class($b);
echo '<br />';
$c = C::getInstance();
echo echo 'class: '.get_class($c);
?>
This returns:
class: b
class: c
http://php.net/manual/en/function.get-class.php