[Zope-CMF] trouble applying extension profiles

[Rob Miller]

maybe i'm missing something fundamental, but i'm having trouble figuring 
out how i'm supposed to apply extension profiles to my site.  the 
intended mechanism is clear enough; set the active configuration to be 
the desired profile and then execute runAllImportSteps on the setup 
tool.  the apparent fuzziness of the boundary between the base profile 
and the extension profiles seem to be getting in my way, however.

my base profile is a default Plone site, which does a bunch of 
configuration and adds a few pieces of content using the "structure" 
folder mechanism that is supported by CMFCore's 
StructureFolderWalkingAdapter.  this works w/o problem.  then i specify 
an extension profile to be the active configuration and again 
runAllImportSteps.  the content is purged by default, which seems odd, 
and it is not recreated b/c the StructureFolderWalkingAdapter is now 
looking for a 'structure' folder in the extension profile, which is the 
wrong place.

i see three possible ways around this, which i'll list in order from my 
least to most preferred:

- we could have extension profiles not purge any content by default.  it 
seems strange that they do.  perhaps this is supposed to be the case 
already, and either it's just not happening or there's something i've 
missed within my setup that is causing it to not be the case.

- allow extension profiles to specify which of the base profile's import 
steps they depend on, so that only these can be run, instead of the 
current situation where, AFAICT, you have to either run them all or 
manually examine the profile and select the steps to run

- draw a more clear distinction between the base profile and the 
extension profiles.  instead of having the extension profiles 
piggy-backing on the base profile, extension profiles would explicitly 
define all of their own import steps, so that they can be applied 
cleanly on top of existing sites w/o becoming quite so muddled w/ the 
default configuration.  this would also make it easier to implement an 
uninstall process that would remove the extension profile from the site.

again, it's possible i'm missing something about the way this is 
supposed to be working.  are these ideas sensible at all?

-r