题
如果PHP失败,有没有办法从SPL自动加载器中抛出异常?它似乎在PHP 5.2.11下工作。
class SPLAutoLoader{
public static function autoloadDomain($className) {
if(file_exists('test/'.$className.'.class.php')){
require_once('test/'.$className.'.class.php');
return true;
}
throw new Exception('File not found');
}
} //end class
//start
spl_autoload_register( array('SPLAutoLoader', 'autoloadDomain') );
try{
$domain = new foobarDomain();
}catch(Exception $c){
echo 'File not found';
}
当调用上述代码时,没有例外的迹象,相反,我会得到标准的“致命错误:类'Foobardomain'在BLA中未找到”。脚本的执行终止。
解决方案
这不是一个错误,它是 设计决定:
笔记: :抛出异常
__autoload
功能不能抓住catch
阻止并导致致命错误。
原因是可能有一个以上的自动加载处理程序,在这种情况下,您不希望第一个处理程序抛出异常并绕过第二处理程序。您希望第二个处理程序有机会自动加工其课程。如果您使用使用自动加载功能的库,则不希望它绕过自动加载处理程序,因为它们会在自动加载器中抛出异常。
如果要检查是否可以实例化课程,请使用 class_exists
并通过 true
作为第二个论点(或排除在外, true
是默认值):
if (class_exists('foobarDomain', $autoload = true)) {
$domain = new foobarDomain();
} else {
echo 'Class not found';
}
其他提示
根据评论 SPL_AUTOLOAD_REGISTER的文档, ,可以从自动加载器中调用另一个功能,这反过来会引发异常。
class SPLAutoLoader{
public static function autoloadDomain($className) {
if(file_exists('test/'.$className.'.class.php')){
require_once('test/'.$className.'.class.php');
return true;
}
self::throwFileNotFoundException();
}
public static function throwFileNotFoundException()
{
throw new Exception('File not found');
}
} //end class
//start
spl_autoload_register( array('SPLAutoLoader', 'autoloadDomain') );
try{
$domain = new foobarDomain();
}catch(Exception $c){
echo 'File not found';
}
这是一个成熟的工厂对象,该对象演示了自动加载,名称支持,非静态实例(带有可变路径)的可可,负载错误的处理和自定义异常。
abstract class AbstractFactory implements \ArrayAccess
{
protected $manifest;
function __construct($manifest)
{
$this->manifest = $manifest;
}
abstract function produce($name);
public function offsetExists($offset)
{
return isset($this->manifest[$offset]);
}
public function offsetGet($offset)
{
return $this->produce($offset);
}
//implement stubs for other ArrayAccess funcs
}
abstract class SimpleFactory extends AbstractFactory {
protected $description;
protected $path;
protected $namespace;
function __construct($manifest, $path, $namespace = "jj\\") {
parent::__construct($manifest);
$this->path = $path;
$this->namespace = $namespace;
if (! spl_autoload_register(array($this, 'autoload'), false)) //throws exceptions on its own, but we want a custom one
throw new \RuntimeException(get_class($this)." failed to register autoload.");
}
function __destruct()
{
spl_autoload_unregister(array($this, 'autoload'));
}
public function autoload($class_name) {
$file = str_replace($this->namespace, '', $class_name);
$filename = $this->path.$file.'.php';
if (file_exists($filename))
try {
require $filename; //TODO add global set_error_handler and try clause to catch parse errors
} catch (Exception $e) {} //autoload exceptions are not passed by design, nothing to do
}
function produce($name) {
if (isset($this->manifest[$name])) {
$class = $this->namespace.$this->manifest[$name];
if (class_exists($class, $autoload = true)) {
return new $class();
} else throw new \jj\SystemConfigurationException('Factory '.get_class($this)." was unable to produce a new class {$class}", 'SYSTEM_ERROR', $this);
//an example of a custom exception with a string code and data container
} else throw new LogicException("Unknown {$this->description} {$name}.");
}
function __toString() //description function if custom exception class wants a string explanation for its container
{
return $this->description." factory ".get_class($this)."(path={$this->path}, namespace={$this->namespace}, map: ".json_encode($this->manifest).")";
}
}
最后是一个例子:
namespace jj;
require_once('lib/AbstractFactory.php');
require_once('lib/CurrenciesProvider.php'); //base abstract class for all banking objects that are created
class CurrencyProviders extends SimpleFactory
{
function __construct()
{
$manifest = array(
'Germany' => 'GermanBankCurrencies',
'Switzerland' => 'SwissBankCurrencies'
);
parent::__construct($manifest, __DIR__.'/CurrencyProviders/', //you have total control over relative or absolute paths here
'banks\');
$this->description = 'currency provider country name';
}
}
现在做
$currencies_cache = (new \jj\CurrencyProviders())['Germany'];
或者
$currencies_cache = (new \jj\CurrencyProviders())['Ukraine'];
logicexception(“未知货币提供商国家名称乌克兰”)
如果没有 /货币提供者 /
jj systemConfigurationException('工厂JJ Currency Providers无法生产新的类银行 SwissCurrencies。调试数据:货币提供商国家名称工厂JJ Currency Providers(Path =/var/var/var/www/www/steret/stite /.../ currency -providers/../ ,名称空间=银行,地图:{“德国”:“ dermanbankcurrencies”,“瑞士”:“ swissbankcurrencies”}')
通过足够的努力,该工厂可以扩展以捕获解析错误(如何在PHP中捕获require()或includ()的错误?)并将论据传递给构造函数。