The Google flags parser (available for Python and C++) is very powerful. I use it for all my projects at work (of course) and since it has been open sourced, I use it for personal projects too.
While I support open source 100% I rarely get to submit much code into other people's projects (I contribute to documentation more than code... go figure). So, even though it is only a few lines of new code, I do want to point out that the 1.6 release of the Python library has actual code from me.
One of the neat features of this flags library is that you can specify a file to read the flags from. That is, if your command line is too long, you can stick all or some of the flags in a file and specify "--flagfile path/to/file.flags" to have them treated as if you put them on the command line. Imagine having one flags file that you use in production and another one that points the server to a test database using a higher level of debug verbosity and enabling beta features. You can specify multiple files even with overlapping flags and it does the right thing, keeping the last value.
My patch was pretty simple. I discovered, through a painful incident, that if the flagfile were silently skipped if they were not readable. No warning, no error message. (You can imagine that my discovery was during a frantic "why is this not working???" afternoon.). Anyway... now you get an error instead and the program stops (in python terms... it raises an exception). I think the unit tests are bigger than the actual code but I'm glad the patch was accepted. I hope nobody was depending on this bug as a "feature". Seriously... nobody would turn off flags via "chmod 000 filename.flags", right? So far I haven't gotten any complaints.
Anyway... if you write code in C++ or Python I highly recommend you give gflags a try. Both are available under the New BSD License on Google Code:
Enjoy!
--Tom
