These are rather nasty workarounds, to be honest. Instantiating a map out of the blue is clever, but not very readable (not to mention potential performance concerns eg. if it's code executing in a large loop), and something I'd definitely call out in code review. Note that computing "this" and "that" could by itself be costly, and one of these values is guaranteeed to get discarded.
I've used the map thing a few times, but sparingly. Mostly for things like setting something based on the value of a boolean commandline flag and the like where the performance impact doesn't matter and keeping it on one line offsets the "ugliness" of the construct. You should indeed avoid it for most other things.
