这个警告与现实世界无关。忘记学术例子,看一个真实的例子。有成千上万的锁制造商生产带组合触摸板和钥匙备用的门锁。他们会使用两个死锁 - 一个用于组合锁,一个用于钥匙锁吗?不会。死锁被抽象为钥匙锁和组合锁。这就是现实世界。PHP(对于这个问题很快拒绝任何错误报告)想在这个问题上把头埋进沙子里。
class abstractLock
{
private $locked = true;
public function unlock()
{
$this->locked=false;
}
public function lockStatus()
{
if($this->locked) return "Locked\n";
else return "Unlocked\n";
}
}
class combinationLock extends abstractLock
{
private $combination = '32-10-21'; // combination
public function unlock($combination) // unlock WITH combination
{
if($this->combination == $combination) parent::unlock();
}
}
class paddleLock extends abstractLock
{
private $key = '100,70,80,30,50,90,60,40,100'; // ridge heights
public function unlock($key) // unlock WITH key
{
if($this->key == $key) parent::unlock();
}
}
$lock1 = new paddleLock();
echo "paddleLock is " . $lock1->lockStatus();
$lock1->unlock('100,70,80,30,50,90,60,40,100');
echo "paddleLock is " . $lock1->lockStatus();
$lock2 = new combinationLock();
echo "combinationLock is " . $lock2->lockStatus();
$lock2->unlock('32-10-21');
echo "combinationLock is " . $lock2->lockStatus();
PHP不愿意讨论这个问题。因此,我的所有代码都将包含以下内容,以消除这个PHP bug:
if (PHP_MAJOR_VERSION >= 7) {
set_error_handler(function ($errno, $errstr) {
return strpos($errstr, 'Declaration of') === 0;
}, E_WARNING);
}
class B extends A
和class Y extends X
才能使你的示例合法。 - nickb