How to separate logging logic from business logic in a C program? And in a C++ one?

Question

I am currently coding in C and I have lots of printfs so that I can track, at some times, the flow of my application. The problem is that some times I want more detail than others, so I usually spend my time commenting/uncommenting my C code, so I can get the appropriate output.

When using Java or C#, I can generally separate both my implementation code from the logging logic by using Aspects.

Is there any similar technique you use in C to get around this problem?

I know I could put a flag called DEBUG that could be either on or off, so I wouldn't have to go all around and comment/uncomment my whole code every time I want to either show or hide the printfs. The question is I'd like to also get rid of the logging logic in my code.

If instead of C I was coding in C++, would it be any better?

Edit

It seems there is an AspectC++, so for C++ there seems to be a solution. What about C?

Thanks

Answer 1

IME you cannot really separate logging from the algorithms that you want to log about. Placing logging statements strategically takes time and experience. Usually, the code keeps assembling logging statements over its entire lifetime (though it's asymptotic). Usually, the logging evolves with the code. If the algorithm changes often, so will usually the logging code.

What you can do is make logging as unobtrusive as possible. That is, make sure logging statements always are one-liners that do not disrupt reading the algorithm, make it so others can insert additional logging statements into an existing algorithm without having to fully understand your logging lib, etc.

In short, treat logging like you treat string handling: Wrap it in a nice little lib that will be included and used just about everywhere, make that lib fast, and make it easy to use.