[Python-Dev] Install-on-first-use vs. optional extensions

["Martin v. Löwis"]

Garth wrote:
> Couldn't you conditionally run  RegisterExtensionInfo?

This is what I currently do (see msi.py:build_database).
Unfortunately, it doesn't work: Installer then unconditionally
runs UnregisterExtensionInfo first, which removes any old
extension information before installing a new one.

Now, this could also be made conditional, although defining
the condition is difficult: If the user changes the extension
from "installed" to "absent", UnregisterExtensionInfo *should*
run. In any case, uninstalling the entire package (i.e.
executing the toplevel REMOVE action) doesn't run the
InstallExecuteSequence (I believe), which further complicates
issues.

I've played with a number of options, and could not make it
to work. I have given up now, but if you find a solution,
please let me know.

Regards,
Martin