[Zope-CMF] Re: [dev] RFC: rethinking GenericSetup extension profiles

[yuppie]

Hi Martin!


GenericSetup uses a completely different approach than 
CMFQuickInstaller. It is focused on states, not on changes.

The early versions of GenericSetup (FKA CMFSetup) didn't even have 
extension profiles and importVarious handlers. I invented those hacks to 
give GenericSetup more momentum, but especially importVarious was never 
meant as a permanent solution. The GenericSetup UI is counter-intuitive 
because it was built for complete profiles/snapshots. importVarious is 
dangerous because it is a hack.

I know that so far GenericSetup can't replace CMFQuickInstaller. But the 
fact people are missing CMFQuickInstaller functionality doesn't mean it 
has to be implemented following the old patterns.

Install/uninstall code for CMFQuickInstaller is hard to write, usually 
only add-on programmers do that. Just replacing python code by XML-files 
will not make it much easier.


And now regarding your concerns:

- I don't think we should use the same machinery for configuration data 
and content. (I know the distinction is fuzzy, but the big mass is pure 
content.) AFAICS it is not very hard to specify areas that contain 
content and should not be touched if profiles are reapplied.

- The procedure I have in mind depends on the ability to create 
customization snapshots. As a first step the setup tool would create 
this snapshot. In the next step it would combine all dependencies of 
that snapshot minus uninstalled extensions plus new extensions. The 
result is a profile that contains the latest data of all selected 
profiles plus the customizations from the snapshot. This profile would 
be used to reset the site.

- Speed is not that important. It doesn't hurt if it takes a few seconds 
until a profile is installed or uninstalled. There are a few very 
expensive tasks like creating indexes. The handler can make sure indexes 
are not removed if the new profile needs the same index.

- I don't know if we really need a way to reset specific products. 
AFAICT the more common use case is to reset specific objects like tools. 
I'd prefer a tab on the object that allows to load preconfigured 
settings instead of using the setup tool for that.

- While I hope we can get rid of importVarious it would be less 
dangerous to use if only complete profiles are applied to the site.


Cheers,

	Yuppie