PHP类常量似乎总是被解释为字符串(PHP class constants seems to always be interpreted as strings)

 类常量似乎总是被解释为字符串，尽管它被定义为整数。 为什么PHP会做这种类型的杂耍，我该如何防止它？ 
 
 请参阅以下代码： 
 
class BitSet {
  const NONE = 0;
  const FOO = 1;
  const BAR = 2;
  const ALL = 3;

  public function __construct( $flags = self::NONE ) {
    if( $flags & self::ALL !== $flags )
      throw new \OutOfRangeException( '$flags = '.$flags.' is out of range' );
    $this->value = $flags;
  }

  protected $value = self::NONE;
}

$bs = new BitSet( BitSet::FOO );
 
 最后一行（构造函数的调用）抛出OutOfRangeException ： 
 
PHP Fatal error:  Uncaught exception 'OutOfRangeException' with message '$flags = 1 is out of range' in test-case.php:12
Stack trace:
#0 /srv/www/matthiasn/class-constant-debug.php(19): BitSet->__construct('1')
#1 {main}
thrown in /srv/www/matthiasn/class-constant-debug.php on line 12
 
 正如你可以从backtrace条目＃0清楚地看到的那样，常量BitSet::FOO作为字符而不是整数传递。 因此，位掩码操作$flags & self::ALL !== $flags不对整数执行，而是在按位ASCII表示上执行，因此失败。 
 
 我勒个去？！ 有没有更好的方法来做到这一点，而不是到处做一个明确的(int)广播？ 

A class constant always seems to be interpreted as a string although it is defined as an integer. Why does PHP do this kind of type juggling and how do I prevent it?
 
See the following code:
 
class BitSet {
  const NONE = 0;
  const FOO = 1;
  const BAR = 2;
  const ALL = 3;

  public function __construct( $flags = self::NONE ) {
    if( $flags & self::ALL !== $flags )
      throw new \OutOfRangeException( '$flags = '.$flags.' is out of range' );
    $this->value = $flags;
  }

  protected $value = self::NONE;
}

$bs = new BitSet( BitSet::FOO );
 
The last line (the invocation of the constructor) throws the OutOfRangeException:
 
PHP Fatal error:  Uncaught exception 'OutOfRangeException' with message '$flags = 1 is out of range' in test-case.php:12
Stack trace:
#0 /srv/www/matthiasn/class-constant-debug.php(19): BitSet->__construct('1')
#1 {main}
thrown in /srv/www/matthiasn/class-constant-debug.php on line 12
 
As you can clearly see from backtrace entry #0 the constant BitSet::FOO is passed as a character not as an integer. Hence, the bit mask operation $flags & self::ALL !== $flags is not performed on integers but on the bitwise ASCII representation and therefore fails.
 
What the hell?! Is there any better way to get this right than to do an explicit (int)-cast everywhere?

原文：