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.

result.process()

That doesn’t make logical sense. You already have a result. It shouldn't need processing to be a result.

It also doesn't make sense for `process()` to be an attribute of `result`. Why would you instantiate a class and call it result‽