类与对象(PHP5)之十一：最终关键字(Final Keyword)
日期:2006-09-26 作者:喜腾小二 来源:PHPChina
PHP5引入了最终关键字，防止子类使用final从一个重要的方法做定义的前缀。如果类本身已经被定义为final,类将不能被扩展。
例子
19-28.Final方法实例
PHP代码如下:
php
class BaseClass
{ public function test()
{
echo "BaseClass::test() called
";
}
final public function moreTesting()
{
echo"BaseClass::moreTesting() called
";
}
}
class ChildClass extends BaseClass
{
public function moreTesting()
{
echo "ChildClass::moreTesting() called
";
}
}
//Results in Fatal error:Cannot override final method BaseClass::moreTesting()
?>
例子 19-29. Final 类实例
PHP代码如下:
php
final class BaseClass
{ public function test()
{
echo "BaseClass::test() called
";
}
//Here it doesn't matter if you specify the function as final or not
final public function moreTesting()
{
echo"BaseClass::moreTesting() called
";
}
}
class ChildClass extends BaseClass { }
//Results in Fatal error:Class ChildClass may not inherit from final class (BaseClass)
?>
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