John Wiegley <johnw@gnu.org> schrieb am Di., 15. Mai 2018 um 21:40 Uhr:

I'd like to create a module, propagate.el, which defines a new class of buffer
local variables: buffer local variables that propagate to any buffers or
processes (in the case of exec-path and process-environment) created on behalf
of the parent.

There is some pior art to this (namely, `default-directory'), but such a facility needs to be very carefully designed because it changes fundamental aspects of ELisp in a subtle way. For example, callers of `with-temp-buffer' can currently assume that buffer-local variables are take from their global defaults and not from the "parent" buffer. This needs to stay that way. So probably such an inheritance facility should be opt-in and not affect existing code.

Before jumping to implementation discussions, we should analyze the precise requirements for such a facility and make sure it's not a breaking change.