I've done this in C with the C preprocessor and Java with m4[0]. The upside of doing it natively is that it keeps the build simpler. And everybody at least kno

I've done this in C with the C preprocessor and Java with m4[0]. The upside of doing it natively is that it keeps the build simpler. And everybody at least knows about the existence of the C preprocessor, even if they don't know it well. And it's fairly limited, which prevents you from getting too clever. The big downside of doing it with the C preprocessor is that the resulting code looks like vomit if it's more than a line or two because of the lack of line breaks in the generated code. Debugging it is unenjoyable. I'd recommend against doing anything super clever. The upside of doing it out of band is that your generated source files look decent. m4 tends to introduce a little extra whitespace, but it's nothing objectionable. Plus you get more power if you really need it. The downside is that almost nobody knows m4[1]. If you choose something else, it becomes a question of what, does anyone else know it, and is it available everywhere you need to build. Honestly, integrating m4 into the build in ant really wasn't too bad. We were building on one OS on two different architectures. For anything truly cross-platform, you'll likely run into all the usual issues. ETA: Getting an IDE to understand the out of band generation might be a hassle, as other folks have mentioned. I'm a vim kinda guy for most coding, and doing it either way was pretty frictionless. The generated java code was read-only and trivial, so there wasn't a lot of reason to ever look at it. By the time you get to debugging, it would entirely transparent because you're just looking at another set of java files. [0] This was so long ago, I no longer remember why it seemed like a good idea. I think there was an interface, a trivial implementation, and some other thing? Maybe something JNI-related? At least at first, things were changing often enough that I didn't want to have to keep three things in sync by hand. [1] Including me. I re-learn just enough to get done with the job at hand every time I need it.