1.final關鍵字(不能修飾屬性,即變量)
a.希望一個類不被其他類來繼承(出於安全性)
案例1:
<?php final class A { } class B EXTENDS A //此用法爲錯誤 { ECHO "OK"; } ?>
結果:
Parse error: syntax error, unexpected T_ECHO, expecting T_FUNCTION in E:\Software_default\wamp_wwwroot\interface\interface05.phpon line 8
來自 <http://localhost/interface/interface05.php>
b.希望某個方法,不被子類改寫,用final,對比案例2,案例3結果
案例2:沒有重寫
<?php class A { public function getrate($salary) { return $salary; } } class B extends A { } $b=new B(); echo $b->getrate(100); ?>
結果:
100
來自 <http://localhost/interface/interface06.php>
案例3:覆蓋
<?php class A { public function getrate($salary) { return $salary; } } class B extends A // { public function getrate($salary) { return $salary*100; } } $b=new B(); echo $b->getrate(100); ?>
結果:
10000
來自 <http://localhost/interface/interface07.php>
案例4:禁止重寫
<?php class A { final public function getrate($salary) { return $salary; } } class B extends A { public function getrate($salary) { return $salary*100; } } $b=new B(); echo $b->getrate(100); ?>
結果:
Fatal error: Cannot override final method A::getrate() in E:\Software_default\wamp_wwwroot\interface\interface08.phpon line 16
來自 <http://localhost/interface/interface08.php>