Operational attribute plugins

[Luke Howard <lukeh@PADL.COM>]

Another really useful plugin type would be for operational/virtual
attributes. The Sun ONE 5.x SLAPI has quite a complicated virtual
attribute API, and I suppose it makes sense to maintain parity 
with them (being the closest thing to a "standard" for SLAPI) but
something simpler would be just as good.

Recall that a search plugin is no use as only one code path can
call slap_send_search_entry(). I was thinking of defining a new
type of plugin, and having slap_send_search_entry() call these
plugins with the to-be-sent entry and allow them to return an
Entry to be coalesced with the entry returned from the backend.

(Because the backend owns the entry, I don't think we could have
a plugin actually modify it.)

Thoughts?

-- Luke

--
Luke Howard | PADL Software Pty Ltd | www.padl.com