============================== The current component registry ============================== There can be any number of component registries in an application. One of them is the global component registry, and there is also the concept of a currently used component registry. Component registries other than the global one are associated with objects called sites. The ``zope.component.hooks`` module provides an API to set and access the current site as well as manipulate the adapter hook associated with it. As long as we haven't set a site, none is being considered current: >>> from zope.component.hooks import getSite >>> print getSite() None We can also ask for the current component registry (aka site manager historically); it will return the global one if no current site is set: >>> from zope.component.hooks import getSiteManager >>> getSiteManager() Let's set a site now. A site has to be an object that provides the ``getSiteManager`` method, which is specified by ``zope.component.interfaces.IPossibleSite``: >>> from zope.component.registry import Components >>> class Site(object): ... def __init__(self): ... self.registry = Components('components') ... def getSiteManager(self): ... return self.registry >>> from zope.component.hooks import setSite >>> site1 = Site() >>> setSite(site1) After this, the newly set site is considered the currently active one: >>> getSite() is site1 True >>> getSiteManager() is site1.registry True If we set another site, that one will be considered current: >>> site2 = Site() >>> site2.registry is not site1.registry True >>> setSite(site2) >>> getSite() is site2 True >>> getSiteManager() is site2.registry True Finally we can unset the site and the global component registry is used again: >>> setSite() >>> print getSite() None >>> getSiteManager()