如何在PHP类型提示中捕获"可捕获的致命错误"？

Question

我试图在我的一个类上实现PHP5的类型提示,

class ClassA {
    public function method_a (ClassB $b)
    {}
}

class ClassB {}
class ClassWrong{}

正确用法:

$a = new ClassA;
$a->method_a(new ClassB);

产生错误:

$a = new ClassA;
$a->method_a(new ClassWrong);

可捕获的致命错误:传递给ClassA的参数1 :: method_a()必须是ClassB的一个实例,ClassWrong的实例给出...

我是否可以知道是否有可能发现错误(因为它说"可捕获")？如果是,怎么样？

谢谢.

Answer 1

更新:这不再是一个可捕获的致命错误在PHP 7.而是抛出"异常"."异常"(在吓唬引号中),不是从Exception但是Error中派生的; 它仍然是一个Throwable,可以用普通的try-catch块来处理.请参阅https://wiki.php.net/rfc/throwable-interface

例如

<?php
class ClassA {
  public function method_a (ClassB $b) { echo 'method_a: ', get_class($b), PHP_EOL; }
}
class ClassWrong{}
class ClassB{}
class ClassC extends ClassB {}


foreach( array('ClassA', 'ClassWrong', 'ClassB', 'ClassC') as $cn ) {
    try{
      $a = new ClassA;
      $a->method_a(new $cn);
    }
    catch(Error $err) {
      echo "catched: ", $err->getMessage(), PHP_EOL;
    }
}
echo 'done.';

版画

catched: Argument 1 passed to ClassA::method_a() must be an instance of ClassB, instance of ClassA given, called in [...]
catched: Argument 1 passed to ClassA::method_a() must be an instance of ClassB, instance of ClassWrong given, called in [...]
method_a: ClassB
method_a: ClassC
done.

pre-php7版本的旧答案:
http://docs.php.net/errorfunc.constants 说:

E_RECOVERABLE_ERROR(整数)
可捕获的致命错误.它表示发生了可能存在危险的错误,但未使引擎处于不稳定状态.如果错误未被用户定义的句柄捕获(另请参见set_error_handler()),则应用程序将中止,因为它是E_ERROR.

另见:http://derickrethans.nl/erecoverableerror.html

例如

function myErrorHandler($errno, $errstr, $errfile, $errline) {
  if ( E_RECOVERABLE_ERROR===$errno ) {
    echo "'catched' catchable fatal error\n";
    return true;
  }
  return false;
}
set_error_handler('myErrorHandler');

class ClassA {
  public function method_a (ClassB $b) {}
}

class ClassWrong{}

$a = new ClassA;
$a->method_a(new ClassWrong);
echo 'done.';

版画

'catched' catchable fatal error
done.

编辑:但你可以"使"它成为你可以使用try-catch块处理的异常

function myErrorHandler($errno, $errstr, $errfile, $errline) {
  if ( E_RECOVERABLE_ERROR===$errno ) {
    echo "'catched' catchable fatal error\n";
    throw new ErrorException($errstr, $errno, 0, $errfile, $errline);
    // return true;
  }
  return false;
}
set_error_handler('myErrorHandler');

class ClassA {
  public function method_a (ClassB $b) {}
}

class ClassWrong{}

try{
  $a = new ClassA;
  $a->method_a(new ClassWrong);
}
catch(Exception $ex) {
  echo "catched\n";
}
echo 'done.';

请参阅:http://docs.php.net/ErrorException