[Zope-CMF] [dev] tools-as-utilities roadmap

[yuppie]

Hi!


After some back and forth CMF 2.1 will just mark the first step of the 
tools-as-utilities refactoring. We now have a working 
five.localsitemanager that adjusts the persistent components registries 
to Zope 2, but right now only a few CMF tools can be used as utilities. 
Many tool methods depend on self.REQUEST, which is not available in 
utilities.

The current state makes things more complex, not easier. So we need to 
move on:


Scenario 1:
-----------

We declare all tool methods that use self.REQUEST instead of an explicit 
REQUEST argument as broken. And fix the tools by adding new REQUEST 
arguments. I guess one or two dozen methods would need that change in 
CMF, many more in third party products.

We can add these arguments as optional arguments in CMF 2.1 and make 
them required after a deprecation period. If you use only tools shipped 
with CMF or adjusted to the new policy, you can start using getUtility 
in CMF 2.1. If not, CMF 2.3 will be the first release that allows to use 
getUtility for all tools.

Pros: The changes are simple, in CMF 2.3 we are done.

Cons: A lot of code needs to be modified. Especially third party code.


Scenario 2:
-----------

We make dual use of tools. Each tool provides a tool interface (e.g. 
IMembershipTool) and an utility interface (e.g. IMembershipUtility). In 
most cases the utility interface will be a subset of the tool interface. 
In the long run, tool methods that are not valid utility methods need to 
be replaced by new utility methods or browser views.

We should add these new utility interfaces for all tools in CMF 2.1 and 
use these instead of the tool interfaces for registering utilities. And 
'getToolByInterfaceName' should be renamed to 'getUtilityByInterfaceName'.

getUtilityByInterfaceName('IMembershipUtility') would return the same 
object as getToolByName(context, 'portal_membership'), but with a 
different wrapper and less methods available.

Pros: No deprecation warnings, nobody is forced to switch to utilities.

Cons: This will take much longer, everybody has to work with tools and 
utilities side by side for a long time. Might be confusing.


Opinions? Questions? Other scenarios?


Cheers,

	Yuppie