To clarify, I mean writing scripts that generate or modify classes for you instead of manually writing them every time, for example if you want to replace reflection with a ton of verbose repetitive code for performance reasons I guess?

My only experience with this is just plain old manual txt generation with something like python, and maintaining legacy t4/tt VS files but those are kind of a nightmare.

What's a good modern way of accomplishing this, have there been any improvements in this area?