[Zope-dev] Stacking zope.component registries

[Martin Aspeli]

Hi,

I'd like to come up with a way to set up a test fixture that does the 
component registry equivalent of stackable DemoStorage's: whilst a layer 
is in effect, calls to provideAdapter() and friends (and ZCML execution) 
go into a global registry that is stacked on top of the default global one.

On layer tear-down, the registry is popped, leaving the original (or 
previous) global registry intact.

In zope.component.globalregistry, I see:

def provideUtility(component, provides=None, name=u''):
     base.registerUtility(component, provides, name, event=False)

base is a module-level variable of type BaseGlobalComponents(). I guess 
there'd be a way to use __bases__ to create this kind of stack, but I'm 
not clear on the details, and in particular whether this would really 
work with provideAdapter() and the rest of the (test-oriented) Python API.

Martin