Question

I run into this problem periodically, and I’m trying to figure out if it’s a configuration issue or a peculiarity with PHP.

Basically, there will be a function foo() defined somewhere in my code, and then elsewhere I will accidentally define a function again with the same name foo(). I would expect an error of some kind to be thrown, e.g. “Fatal Error: Function already defined line 234, bar.php blah blah”.

But I get nothing. I just get a blank screen. Debugging can take an eternity as I try to pinpoint exactly where the function is being accidentally redefined, without help from an error message.

My config settings for reporting errors are set to E_ALL, and I see all other kinds of errors without a hitch.

Any insights? Is there anything I can do to cause PHP to report these errors (so that I can either rename the offending function or wrap it in an if function_exists() clause)?

Edit: To be clear, I understand the many strategies to avoid namespace collisions in PHP. I’m talking about instances where for whatever reason I accidentally name a function a name that already exists during development (or for example I import a file where a function has already been defined). I would expect an error message when this occurs, which would help me debug, but I do not get one.

Answer 1

You can wrap function definitions in a conditional function_exists():

if (!function_exists("file_get_contents"))
 {
   function file_get_contents(....)
     ....
 }

works for me.

You could wrap a function_exists check around each function and have it throw an error message if it already exists. The better way however would be finding out why fatal errors don’t appear on screen. Can you check phpinfo() for the error_reporting and related settings?

This is what you should be getting when trying to redefine a function:

Fatal error: Cannot redeclare file_get_contents() in D:\xyz\htdocs\test.php on line 5

From my phpinfo():

display_errors On

error_reporting 22519 (equals… well, I don’t know but it shows errors 🙂

In some hosting environments when error reporting was turned off completely, I have found defining a custom error handler very helpful: set_error_handler()