[Evolution] Making EDS find external EWS plugin

[Bjørn Forsman <bjorn forsman gmail com>]

Hi Evolution Developers,

Is there a way to make EDS (evolution-data-server) pick up an exteranl
EWS plugin? That is, find the plugin *without* it being located inside
evolution-data-server installation tree?

I'm hitting this problem when packaging EWS with the Nix package
manager[1]. In Nix, each package install tree is immutable (read-only)
after installation. So E + EDS + EWS currently pose a circular
dependency which I'm unable to solve, unless building *all three*
packages at the same time, into one install tree.

I was hoping there was an environment variable to locate external
plugins. I found some environment variable documentation here:
https://wiki.gnome.org/Apps/Evolution/Debugging. But that is only
about debugging, not about finding external plugins. I downloaded the
source code of EDS and grepped for "getenv". I didn't find anything
promising.

Can you point me in the direction where EDS finds its plugins (in the
source code)?

Best regards,
Bjørn Forsman

[1]: http://nixos.org/nix/