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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