The early C++ compilers generate C code. You might think of them as a fancy sort of macro program.

M4 is a macro languge for generating HTML.

If you study the pages on this website, you will see much of the html was generated with macros. For example <!-- macro Foot --> expands to about 40 lines of mostly boilerplate at the bottom of each page. The macro themselves are written in Java. I have not so far released this code to the public.

Much of the code in my programs I create with little custom programs that I call stompers, programs that take simple input and generate reams of Java bubblegum housekeeping code, e.g. to set up Listeners. This is a one shot deal. I then maintain the generated code as if I had written it by hand. With true macro processors, you never modify the output. You change the input and re-run the macro generation.

If the inputs have not changed, the outputs will be the same. In order to avoid false deltas, I use untouch, to redate the files back to their original dates.