Ken Goldman wrote:
I find that if I put my local .el file directory in load-path ahead of
the system version, it uses mine. So I don't delete old ones. I just
install new ones in my local .el directory.
This mostly works, there are some gotchas though. Defvar does not
change the value of variables that are already defined. So if an old
version of Foo.el sets up variables in a particular way, then when you
load the new version those variables will be set the same way they were
in the old version. Using "unload" too is safer.