Question

I have a function that returns false for many reasons. Is it possible to also make it throw catchable errors without breaking other code relying on it being true or false?

Or will I have to return arrays or return error resasons and only true on success?

What is the best aproach for this?

Some idea based on Daniel’s approach:

__FUNCTION__ should return the functions name

$errors = array();
function someFunction(){
    if(ErrorTWOhappened()){
        global $errors[__FUNCTION__] = "ERRORtwo";
        return false;
    }
    if(someOtherError()){
        global $errors[__FUNCTION__] = "someOtherError";
        return false;
    }
    return true;
}
if(!someFunction())echo $errors['someFunction'];

Answer 1

In order not to break backwards compatibility but to provide more information, you can create a second function to log error messages. In a procedual approach, this could look like this:

$myFunctionErrors = array();
function myFunctionSetError($error) {
    global $myFunctionErrors;
    $myFunctionsErrors[] = $error;
}

function myFunctionGetErrors() {
    global $myFunctionErrors;
    return $myFunctionErrors;
}

And just call myFunctionSetError('whatever'); inside your existing function. Note: myFunction is just a prefix, name it after your real function.

Note also: You could obviously use the array directly. For better maintainability, however, I recommend you using functions you can modify later on to easily change the logic behind it.

If you prefer an object oriented approach, you can also set up a class for that and prevent possible side-effects regarding the global $myFunctionErrors variable.

class MyFunctionErrorLogger
{
    protected static $errors = array();

    public function setError($error)
    {
        self::$errors[] = $error;
    }

    public static function getErrors()
    {
        return self::$errors;
    }
}

Or, if you prefer a “hacked” way, extend the function a little. By adding another function parameter with a false default value. Old function calls won’t be affected by this but you ca provide this extra parameter in your future calls.

function myFunction($myParam, ..., $errorsAsException = false)
{
    // ...
    // Ooops, error case
    if ($errorAsException)
        throw new WhatEverException('errormsg');
    else
        return false;
    // ...
}