yuppie wrote:
Philipp von Weitershausen wrote:
yuppie wrote:
Kapil's also right when he says that utilities by principle are
context-less components.
By principle all Zope 3 code might depend on setSite to work as
expected.
setSite() is something that influences the place (= registry) that we
look up the utilities from. It doesn't influence the "context" of the
utility because tilities have no context. Sure, utilities might be local
and even persistent. But that is a registration detail, not an
implementation detail.
The name "site" in Zope 3 is confusing. "Place with component
registrations" is better. So, let's pretend setSite() was called
updateCurrentComponentRegistryFromPlace(), it becomes pretty obvious
that it has nothing to do with what the utility does. All it does is
tell the Component Architecture which component registry to look up
things. The fact that this registry happens to be associated with a
place in the object hierarchy is completely irrelevant to the Component
Architecture.
We just don't pass that 'site context' explicitly to the
component as in Zope 2.
Right. The utility doesn't even *get* the context (and it shouldn't need
it.) And in Zope 2 we don't pass the context in either. The tools get it
by doing aq_parent(). This should be converted to a lookup, because it's
not about the hierarchy that the tool happened to be placed in, it's
about getting one very specific object: the CMF site.
I still don't buy that context argument. Utilities and tools both are
used in the 'context' of a site.
You just gave the definition of a tool, not the one of a utility.
By 'site context' I don't mean an Zope 2 acquisition context or an
adapter context. I mean the site specific local environment that is
usually looked up based on setSite or provided by CMF tools.
Utilities shouldn't care which "site context" they've been registered
at. If they want a specific object like the CMF site they should look it up.
The only difference is how the knowledge about the site is used: Just
for lookups or also for acquisition wrapping.
If a tool needs to get to the site object in order to operate, it
might not be such a good idea to convert it to a utility. It might
make more sense as an adapter... What I'm saying is that the "all
tools are utilities now" assumption might've been a bit too naive.
Of course CMF tool interfaces have some methods we would not add to a
new utility interface. But most of them would become views, and as long
as we pass in the REQUEST explicitly they are still valid utility methods.
I'm not aware of any tool methods that should be converted to site
adapters. Most tools use the 'site context' just for the security
machinery. The other reason why tools needed the context was looking up
other tools, but that is obsolete in CMF 2.1 beta. I consider every
other usage of the acquisition context a bug.
Good. Then fix those "bugs" and we no longer need any acquisition
wrapping of local utilities at all (and it should be ripped out of
five.localsitemanager again). This would, of course, be an acceptable
solution.
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