Question

The function I’m calling with call_user_func is supposed to return FALSE. So how do I detect errors if the callable is invalid?

(Side note: Why didn’t they have this throw an exception rather than return an error code? Or is there a way to “catch” errors? I have an error handle. Should I have it throw exceptions for me?)

Answer 1

If you want to check if the function or method to be called really exists, you can use is_callable before calling call_user_func. You may wrap the whole thing in a function for easy reuse:

function call_uf($fn) {
    if(is_callable($fn)) {
        return call_user_func($fn);
    } else {
        throw new Exception("$fn is not callable");
    }
}

You asked in a comment about why PHP raises errors instead of using exceptions. I think that’s because exceptions were introduced only in PHP5, so most PHP functions rely on error reporting. There seems to be a way around that, as the manual indicates:

Internal PHP functions mainly use Error reporting, only modern Object oriented extensions use exceptions. However, errors can be simply translated to exceptions with ErrorException.