I've heard a ton of complaining over the years about inherited projects that us developers have to work with. The WTF site has tons of examples of code that make me actually mutter under my breath "WTF?"
But have any of you actually been presented with code that made you go, "Holy crap this was well thought out!" or "Wow, I never thought of that!"
What inherited code have you had to work with that made you smile and why?
I think Rocky Lhotka should get the credit, but I had to touch a CSLA.NET application recently {in my private practice on the side} and I was very impressed with the orderliness of the code. The app worked extremely well, but the client needed a few extensions. The original author had died tragically, and the new guy was unsophisticated. He didn't understand CSLA.NET's business object based approach, and he wanted to do it all over again in cut-and-dried VB.NET, without any fancy framework.
So I got the call. Looking at a working example of WinForm binding and CSLA.NET was pretty instructive about a lot of things.
Some VB6 code by another programmer at my company I came across that handled the error conditions very well (whether it be deal with them directly or log them).
Along with some rather complex code that was well commented.
I know this will bring a lot of answers like,
"I've never find good code before I step in" and variations.
I think the real problem there is not that there isn't good coders or excellent projects out there, is that there's an excess of NIH syndrome and the fact that no body likes code from others. The latter is just because you have to make an intellectual effort to understand it, a much bigger effort than you need to understand you own code so that you dislike it (it's making you think and work after all).
Personally I can remember (as everyone I guess) some cases of really bad code but also I remember some pretty well documented, elegant code.
Currently, the project that most impressed me was a very potent, Dynamic Workflow Engine, not only by the simplicity but also for the way it is coded. I can remember some very clever snippets here and there, as well as a beautiful metaprogramming library based on a full IDL developed by some friends of mine (Aspl.es)
Symbian OS - the old core bit of it anyway, the bit that dated back to the Psion days or those who even today keep that spirit alive.
And sitting right along side it and all over it is all the new crap created by the lowest bidders hired by the big phone corporations. It was startling, you could actually feel in your bones whether a bit of the code-base was old or new somehow.
Long ago, I was responsible for the Turbo C/C++ run-time library. Tanj Bennett wrote the original 80x87 floating point emulator in 16-bit assembler. I hadn't looked closely at Tanj's code since it worked well and didn't require attention. But we were making the move to 32-bits and the task fell to me to stretch the emulator.
If programming could ever be said to have something in common with art this was it.
Tanj's core math functions managed to keep an 80-bit floating point temporary result in five 16-bit registers without having to save and restore them from memory. X86 assembly programmers will understand just what an accomplishment this was. Register space was scarce and keeping five registers as your temp while simultaneously doing complex math was a beautiful site to behold.
If it was only a matter of clever coding that would have been enough to qualify it as art but it was more than that. Tanj had carefully picked the underlying math algorithms that would be most suitable for keeping the temp in registers. The result was a blazing-fast floating point emulator which was an important selling point for many of our customers.
By the time the 386 came along most people who cared about floating-point performance weren't using an emulator but we had to support Intel's 386SX so the emulator needed an overhaul. I rewrote the instruction-decode logic and exception handling but left the core math functions completely untouched.
The code that impresses me the most, and which I try to emulate - is code that seems too simple and easy to understand.
It is damn difficult to write that kind of code. :-)
Ron
I remember when I wrote my bachelor thesis on type inference, my Pascal-to-Pascal 'compiler' was an extension of a Parser my supervisor programmed (in Java). It had a pretty good structure as far as I can remember, and for me who had never done any serious Object-oriented programming, it was quite a revelation.
I have a funny story to tell here.
I was working on this Javaish application, filled with getters & setters that did nothing but get or set and interfaces and everything ever invented to make code unreadable. One day I stumbled upon some code which seemed very well crafted -- it was basically an algorithm implementation that looked very elegant = few lines of readable code, even though it respected every possible rule the project had to adhere to (it was checkstyled automatically).
I couldn't figure out who on the team could have written such code. I was dying to discuss with him and share thoughts. Thankfully, we had switched to subversion (from cvs) a few months earlier and I quickly ran am 'svn blame'. I loled all over the place, seeing my name next to the implementation.
I had heard stories about people not remembering code they wrote 6 months back, code that is a nightmare to maintain. I could not believe such a thing could happen: how can you forget code you wrote? Well, now I'm convinced it can happen. Thankfully the code was alright and easy to extend, so I've only experienced half of the story.
In my first job, I was amazed to discover a "safe ID" class in the codebase (c++), which was wrapping numerical IDs in a class templated with an empty tag class, that ensured that the compiler would complain if you tried for example to compare or assign a UserId into an OrderId.
Not only did I made sure that I had an equivalent Id class in all subsequent codebases I would be using, but it actually opened my eyes on what the compiler could do to guarantee correctness and help writing stronger code.
I inherited a large bunch of code that was SO well written I actually spent the $40 online to find the guy, I went to his house and thanked him.
I've been doing a lot of Eclipse plug-in development and often had to debug into the actual Eclipse source code. While I haven't "inherited" it in the sense that I'm not continuing work on it, I've always been impressed with the design and quality of the early core.