Avoiding magic numbers without creating dependencies

Question

I'm creating an error manager for an API I'm work on. The idea is that it provides a single store of error codes that can be returned from the API, ensuring that the same error in different calls is handled in the same way (e.g. required value missing from the request).

My initial approach was along the lines of:

$this->_errorManager->setError(ErrorCodes::REQUIRED_FIELD);

However this creates a dependency on the error codes class anywhere I want to set an error.

The alternative is:

$this->_errorManager->setError(100);

But now I've got a number sitting in the middle of my code that means nothing.

While I can think of solutions to this specific problem there will be other situations where I will want to use an 'enum' and I can't think of a solution that doesn't tightly couple the classes.

Is there a better way of doing this or a different approach I can take to remove magic numbers? Or is the tight coupling something I just have to accept and consider on a case by case basis?

Answer 1

This is desired coupling. While it is a good idea, to have the application and its error manager loosely coupled, there is no reason to separate the application and its error codes, they belong together.

Dependencies:

+-----------------------+
|Application error codes|<------------+
+-----------------------+             |
           ^                          |
           |                          |
+----------+----------+               |
|Application component|               |
+----------+----------+               |
           |                          |
           v                          |
+-----------------------+     +-------+-----+
|Error handler interface|<|---+Error handler|
+-----------------------+     +-------------+