PHP:如何避免重新声明函数？

Question

我倾向于得到如下错误:

Fatal error: Cannot redeclare get_raw_data_list() (previously declared in /var/www/codes/handlers/make_a_thread/get_raw_data_list.php:7) in /var/www/codes/handlers/make_a_thread/get_raw_data_list.php on line 19

如何避免错误？是否可以创建一个 IF 子句来在声明函数之前检查它是否已声明？

Answer 1

if(!function_exists("get_raw_data_list")) {
... define function here ...
}

http://us.php.net/function_exists