[emacs-berlin] Suggested way to unset/undef/unalias stuff with emacsclient?

[jman]

Michael Heerdegen <michael_heerdegen at web.de> writes:

> You describe a thing that has a psychological nature. In twenty years I
> never heard of anyone where what you describe had a practical
> consequence.  It's more about a feeling that the environment has to be
> cleaned.
>
> If you want to experiment, use a new separate session.  And inside your
> session use the prefix "my-..." for definitions.

Ok, so you're suggesting using "throwaway" definitions when playing and testing and then assign the 
final name when everything works - correct?
Yes, that's certainly a way to workaround the issue, but I find it a bit inelegant.

Let me provide some examples of disadvantages of never restarting emacs:
- I change my mind about the name of a function. I'd rather undefine the old one and only keep the 
  new one. Trivial example, I've recently renamed "my/insert-date-YYYYMMDD" to 
  "my/insert-date-YYYY-MM-DD".
- Some assignments are "additive", example lists. If I make a mistake I can't reset to the original 
  state unless I restart or figure out how to go back to the original state.
- If I enable a package by evaluating a lisp file, how can I remove all that it defined without 
  restarting?
- If I want to test another revision of a package from git, how can I go back to the previous one 
  and be sure there are no leftovers or conflicts?
- How can I test if my init.el is still fine after some changes?
- I want to free up a keymap assignment. Either I unset it or I restart emacs after commenting it 
  out in my config
- sometimes I use the scratch buffer as a playground, often with variables names set globally. If I 
  `(setq result ...)` there's a high risk I am overwriting something else?

These are real examples off the top of my head that I had to deal in the past. How do other emacs 
users deal with these instead?