PHP: how to avoid redeclaring functions?

Question

I tend to get errors such as:

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

how can I avoid the error? Is it possible to create a IF-clause to check whether a function is declared before declaring it?

Answer 1

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

http://us.php.net/function_exists

Answer 2

Use require_once or include_once as opposed to include or require when including the files that contain your functions.

The _once siblings of include and require will force PHP to check if the file has already been included/required, and if so, not include/require it again, thereby preventing 'cannot redeclare x function...' fatal errors.