John Carmack on mutable variables

I try to keep deeper mutation to where it belongs, but I'll admit to shadowing variables pretty often.

If I have a `result` and I need to post-process it. I'm generally much happier doing `result = result.process()` rather than having something like `preresult`. Works nicely in cases where you end up moving it into a condition, or commenting it out to test an assumption while developing. If there's an obvious name for the intermediate result, I'll give it that, but I'm not over here naming things `result_without_processing`. You can read the code.

You're using really generic terms which I have to think is mostly because you're talking about it in the abstract. In most scenarios I find there are obvious non-generic names I can use for each step of a calculation.