So a few months back I was bored one night and dug through the CMake bug tracker looking for something interesting. I came across a request from a user to have CMake generate warnings when undefined variables are encountered. I thought, gee, what a great idea. I've often been bitten by variable name typo bugs before and why doesn't CMake simply give me a warning like most scripting languages out there when an undefined variable is used?<br>
<br>So I dove through the source to try to learn a bit more about CMake works (and see how hard the patch would be to implement). It didn't look that hard to do in the source so I messed around a little and implemented a small patch to enable it. The major catch I discovered was that there are a lot of places where people expect variables to be often undefined and some of these places (i.e. FIND_LIBRARY) it would be unfeasible for a user to introduce IF(DEFINED... ) logic so I introduced a variable keyword that could be used to suppress the warnings. I don't like some of the things I did in the patch looking back at it, but before I forget about it entirely or consider working on it again I wanted to get some feedback from users regarding this idea.<br>
<br>Are undefined variable warnings something that people might want in CMake 2.8.0 (as a default policy) or is the language too far deployed to expect to be able to introduce this feature?<br><br><a href="http://public.kitware.com/Bug/view.php?id=4249">http://public.kitware.com/Bug/view.php?id=4249</a><br clear="all">
<br>-- <br>Philip Lowman