Some Useful C Modules

 I'm working on a non-trivial bit of C programming, and I decided to externally modularize three parts of it as potentially reusable components:

1. err - error-handling module.
2. hmap - hash map module.
3. cfg - configuration file loader module.

All three are intend to be simple and small. Note that "err" has no external dependencies, "hmap" leverages "err" but includes a copy of it in its repo, and "cfg" leverages both "err" and "hmap", and includes copies of them too. I know having all those copies seems wasteful, but C doesn't have the same kind of dependency and versioning infrastructure that Java has, and including the files makes each repo stand-alone.

Of the three, "err" will probably be the least likely to be reused by anybody but me, but in some ways is the most helpful, IMO. To quote from its doc:

The C language does not have a well-established methodology for APIs to report errors. Java has exceptions, but C does not. The closest thing that C has to a common methodology is the Unix common practice in which a function returns certain valid values that represent success (the values can vary according to the API function), and a certain invalid value for failure. Callers are expected to check the return value for validity, and refer to "errno" (when available) for information about the error.

In my experience, that kind of error reporting methodology is a recipe for unreliable programs that are hard to debug and fix. Thousands of lines of code written that call APIs without checking the return status, or does check but only prints something unhelpful even to the code maintainers.

See also my earlier post, "Error handling: the enemy of readability?". Note that the "err" system described here is NOT the same as described in that earlier post, but you'll see similarities. This current "err" system evolved the right way, by putting it to use in non-trivial coding efforts. It is battle-tested and has proven its worth ... at least to me.

Finally, full disclosure, Claude.ai helped me in many ways. A little bit with the coding itself, but much more so in many other ways. See "Claude as Coder's Assistant" for a longer description of how I use Claude.

Finally, as I alluded, the above three modules are just supporting cast members of a larger effort that I've been working on: lsim - a digital logic simulator. It's a hobby project - no self-respecting hardware engineer would actually use it for real work - but it's been a fun couple of months getting it working! And, as an actual user of the above three modules, it has evolved those modules into something more useful than they were when they started. It's hard to make a good API if you don't eat your own dogfood.

You might notice that lsim is not well-documented (ok, the hardware definition language IS well documented, thanks to Claude.ai). This is because lsim, while the most ambitious of these code bases, is also the least likely to have anything usable or re-usable by anybody but me.

If I'm wrong and you would like to take it for a test drive, let me know and I'll give you a hand.