Maybe a comment on the change to sets is in order: I did this because we need only user id/name only once and that way removing a user from the filter is easier.
This kind of breaks backwards compitibility, but only kind of, as Filters.user was not really designed to be mutable.
Then again, I'm not very passionate about that change and can revert it.

Two more things:

1. I just noticed, that Filters.chat currently does pretty much the same as Filters.user. I think it would be good to update it as well. I'll try and set up a base class for the two of them in order to reduce code duplication
2. As it wasn't really discussed yet: We're okay with switching from lists to sets for usernames/ids? Users shouldn't have fiddled with them anyway, so if they if that's their problem? :D

• I just noticed, that Filters.chat currently does pretty much the same as Filters.user. I think it would be good to update it as well. I'll try and set up a base class for the two of them in order to reduce code duplication

good idea. go for it.

• As it wasn't really discussed yet: We're okay with switching from lists to sets for usernames/ids? Users shouldn't have fiddled with them anyway, so if they if that's their problem? :D
  as i see it, whether it's a list or set is an implementation detail. not exposed to the user. (the user may pass anything which we can iterate. we'll convert it into a set)

so what i'm saying, sets are good and for large numbers will provide better performance. in small numbers it wouldn't matter if it's a list or set.

• I just noticed, that Filters.chat currently does pretty much the same as Filters.user. I think it would be good to update it as well. I'll try and set up a base class for the two of them in order to reduce code duplication

good idea. go for it.

on a second thought, having a general solution might be over engineering.
IMHO, you can just copy/paste the code.

• I just noticed, that Filters.chat currently does pretty much the same as Filters.user. I think it would be good to update it as well. I'll try and set up a base class for the two of them in order to reduce code duplication

good idea. go for it.

on a second thought, having a general solution might be over engineering.
IMHO, you can just copy/paste the code.

Okay. But then I'll wait until we're happy with Filters.user, so it's a one time jobe :D

LGTM

Fails unrelated. Merging.

@Bibo-Joshi 💥