類與對象(PHP5)之十一：最終關鍵字(Final Keyword)
日期:2006-09-26 作者:喜騰小二 來源:PHPChina
PHP5引入了最終關鍵字，防止子類使用final從一個重要的方法做定義的前綴。如果類本身已經被定義為final,類將不能被擴展。
例子
19-28.Final方法實例
PHP代碼如下:
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 類實例
PHP代碼如下:
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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