Zope Component Architecture
Project description
This package represents the core of the Zope Component Architecture. Together with the ‘zope.interface’ package, it provides facilities for defining, registering and looking up components.
Releases
3.5.0 (2008-07-25)
Support registration of utilities via factories through the component registry and return factory information in the registration information. This fixes https://bugs.launchpad.net/zope3/+bug/240631
Optimized un/registerUtility via storing an optimized data structure for efficient retrieval of already registered utilities. This avoids looping over all utilities when registering a new one.
3.4.0 (2007-09-29)
No further changes since 3.4.0a1.
3.4.0a1 (2007-04-22)
Corresponds to zope.component from Zope 3.4.0a1.
In the Zope 3.3.x series, zope.component was simplified yet once more. See http://wiki.zope.org/zope3/LocalComponentManagementSimplification for the proposal describing the changes.
3.2.0.2 (2006/04/15)
Fix packaging bug: ‘package_dir’ must be a relative path.
zope.component version 3.2.0.1 (2006/04/14)
Packaging change: suppress inclusion of ‘setup.cfg’ in ‘sdist’ builds.
3.2.0 (2006/01/05)
Corresponds to the verison of the zope.component package shipped as part of the Zope 3.2.0 release.
Deprecated services and related APIs. The adapter and utility registries are now available directly via the site manager’s ‘adapters’ and ‘utilities’ attributes, respectively. Services are accessible, but deprecated, and will be removed in Zope 3.3.
Deprectaed all presentation-related APIs, including all view-related API functions. Use the adapter API functions instead. See http://dev.zope.org/Zope3/ImplementViewsAsAdapters`
Deprecated ‘contextdependent’ package: site managers are now looked up via a thread global, set during URL traversal. The ‘context’ argument is now always optional, and should no longer be passed.
3.0.0 (2004/11/07)
Corresponds to the verison of the zope.component package shipped as part of the Zope X3.0.0 release.
Detailed Documentation
Zope Component Architecture
This package, together with zope.interface, provides facilities for defining, registering and looking up components. There are two basic kinds of components: adapters and utilities.
Utilities
Utilities are just components that provide an interface and that are looked up by an interface and a name. Let’s look at a trivial utility definition:
>>> from zope import interface>>> class IGreeter(interface.Interface): ... def greet(): ... "say hello">>> class Greeter: ... interface.implements(IGreeter) ... ... def __init__(self, other="world"): ... self.other = other ... ... def greet(self): ... print "Hello", self.other
We can register an instance this class using provideUtility [1]:
>>> from zope import component
>>> greet = Greeter('bob')
>>> component.provideUtility(greet, IGreeter, 'robert')
In this example we registered the utility as providing the IGreeter interface with a name of ‘bob’. We can look the interface up with either queryUtility or getUtility:
>>> component.queryUtility(IGreeter, 'robert').greet() Hello bob>>> component.getUtility(IGreeter, 'robert').greet() Hello bob
queryUtility and getUtility differ in how failed lookups are handled:
>>> component.queryUtility(IGreeter, 'ted') >>> component.queryUtility(IGreeter, 'ted', 42) 42 >>> component.getUtility(IGreeter, 'ted') ... # doctest: +ELLIPSIS Traceback (most recent call last): ... ComponentLookupError: (<InterfaceClass ...IGreeter>, 'ted')
If a component provides only one interface, as in the example above, then we can omit the provided interface from the call to provideUtility:
>>> ted = Greeter('ted')
>>> component.provideUtility(ted, name='ted')
>>> component.queryUtility(IGreeter, 'ted').greet()
Hello ted
The name defaults to an empty string:
>>> world = Greeter() >>> component.provideUtility(world) >>> component.queryUtility(IGreeter).greet() Hello world
Adapters
Adapters are components that are computed from other components to adapt them to some interface. Because they are computed from other objects, they are provided as factories, usually classes. Here, we’ll create a greeter for persons, so we can provide personalized greetings for different people:
>>> class IPerson(interface.Interface): ... name = interface.Attribute("Name")>>> class PersonGreeter: ... ... component.adapts(IPerson) ... interface.implements(IGreeter) ... ... def __init__(self, person): ... self.person = person ... ... def greet(self): ... print "Hello", self.person.name
The class defines a constructor that takes an argument for every object adapted.
We used component.adapts to declare what we adapt. We can find out if an object declares that it adapts anything using adaptedBy:
>>> list(component.adaptedBy(PersonGreeter)) == [IPerson] True
If an object makes no declaration, then None is returned:
>>> component.adaptedBy(Greeter()) is None True
If we declare the interfaces adapted and if we provide only one interface, as in the example above, then we can provide the adapter very simply [1]:
>>> component.provideAdapter(PersonGreeter)
For adapters that adapt a single interface to a single interface without a name, we can get the adapter by simply calling the interface:
>>> class Person: ... interface.implements(IPerson) ... ... def __init__(self, name): ... self.name = name>>> IGreeter(Person("Sally")).greet() Hello Sally
We can also provide arguments to be very specific about what how to register the adapter.
>>> class BobPersonGreeter(PersonGreeter): ... name = 'Bob' ... def greet(self): ... print "Hello", self.person.name, "my name is", self.name>>> component.provideAdapter( ... BobPersonGreeter, [IPerson], IGreeter, 'bob')
The arguments can also be provided as keyword arguments:
>>> class TedPersonGreeter(BobPersonGreeter): ... name = "Ted">>> component.provideAdapter( ... factory=TedPersonGreeter, adapts=[IPerson], ... provides=IGreeter, name='ted')
For named adapters, use queryAdapter, or getAdapter:
>>> component.queryAdapter(Person("Sally"), IGreeter, 'bob').greet() Hello Sally my name is Bob>>> component.getAdapter(Person("Sally"), IGreeter, 'ted').greet() Hello Sally my name is Ted
If an adapter can’t be found, queryAdapter returns a default value and getAdapter raises an error:
>>> component.queryAdapter(Person("Sally"), IGreeter, 'frank')
>>> component.queryAdapter(Person("Sally"), IGreeter, 'frank', 42)
42
>>> component.getAdapter(Person("Sally"), IGreeter, 'frank')
... # doctest: +ELLIPSIS
Traceback (most recent call last):
...
ComponentLookupError: (...Person...>, <...IGreeter>, 'frank')
Adapters can adapt multiple objects:
>>> class TwoPersonGreeter: ... ... component.adapts(IPerson, IPerson) ... interface.implements(IGreeter) ... ... def __init__(self, person, greeter): ... self.person = person ... self.greeter = greeter ... ... def greet(self): ... print "Hello", self.person.name ... print "my name is", self.greeter.name>>> component.provideAdapter(TwoPersonGreeter)
To look up a multi-adapter, use either queryMultiAdapter or getMultiAdapter:
>>> component.queryMultiAdapter((Person("Sally"), Person("Bob")),
... IGreeter).greet()
Hello Sally
my name is Bob
Adapters need not be classes. Any callable will do. We use the adapter decorator (in the Python 2.4 decorator sense) to declare that a callable object adapts some interfaces (or classes):
>>> class IJob(interface.Interface): ... "A job">>> class Job: ... interface.implements(IJob)>>> def personJob(person): ... return getattr(person, 'job', None) >>> personJob = interface.implementer(IJob)(personJob) >>> personJob = component.adapter(IPerson)(personJob)
In Python 2.4, the example can be written:
>>> @interface.implementer(IJob) ... @component.adapter(IPerson) ... def personJob(person): ... return getattr(person, 'job', None)
which looks a bit nicer.
In this example, the personJob function simply returns the person’s job attribute if present, or None if it’s not present. An adapter factory can return None to indicate that adaptation wasn’t possible. Let’s register this adapter and try it out:
>>> component.provideAdapter(personJob)
>>> sally = Person("Sally")
>>> IJob(sally) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
TypeError: ('Could not adapt', ...
The adaptation failed because sally didn’t have a job. Let’s give her one:
>>> job = Job() >>> sally.job = job >>> IJob(sally) is job True
Subscription Adapters
Unlike regular adapters, subscription adapters are used when we want all of the adapters that adapt an object to a particular adapter.
Consider a validation problem. We have objects and we want to assess whether they meet some sort of standards. We define a validation interface:
>>> class IValidate(interface.Interface): ... def validate(ob): ... """Determine whether the object is valid ... ... Return a string describing a validation problem. ... An empty string is returned to indicate that the ... object is valid. ... """
Perhaps we have documents:
>>> class IDocument(interface.Interface): ... summary = interface.Attribute("Document summary") ... body = interface.Attribute("Document text")>>> class Document: ... interface.implements(IDocument) ... def __init__(self, summary, body): ... self.summary, self.body = summary, body
Now, we may want to specify various validation rules for documents. For example, we might require that the summary be a single line:
>>> class SingleLineSummary: ... component.adapts(IDocument) ... interface.implements(IValidate) ... ... def __init__(self, doc): ... self.doc = doc ... ... def validate(self): ... if '\n' in self.doc.summary: ... return 'Summary should only have one line' ... else: ... return ''
Or we might require the body to be at least 1000 characters in length:
>>> class AdequateLength: ... component.adapts(IDocument) ... interface.implements(IValidate) ... ... def __init__(self, doc): ... self.doc = doc ... ... def validate(self): ... if len(self.doc.body) < 1000: ... return 'too short' ... else: ... return ''
We can register these as subscription adapters [1]:
>>> component.provideSubscriptionAdapter(SingleLineSummary) >>> component.provideSubscriptionAdapter(AdequateLength)
We can then use the subscribers to validate objects:
>>> doc = Document("A\nDocument", "blah") >>> [adapter.validate() ... for adapter in component.subscribers([doc], IValidate) ... if adapter.validate()] ['Summary should only have one line', 'too short']>>> doc = Document("A\nDocument", "blah" * 1000) >>> [adapter.validate() ... for adapter in component.subscribers([doc], IValidate) ... if adapter.validate()] ['Summary should only have one line']>>> doc = Document("A Document", "blah") >>> [adapter.validate() ... for adapter in component.subscribers([doc], IValidate) ... if adapter.validate()] ['too short']
Handlers
Handlers are subscription adapter factories that don’t produce anything. They do all of their work when called. Handlers are typically used to handle events.
Event subscribers are different from other subscription adapters in that the caller of event subscribers doesn’t expect to interact with them in any direct way. For example, an event publisher doesn’t expect to get any return value. Because subscribers don’t need to provide an API to their callers, it is more natural to define them with functions, rather than classes. For example, in a document-management system, we might want to record creation times for documents:
>>> import datetime>>> def documentCreated(event): ... event.doc.created = datetime.datetime.utcnow()
In this example, we have a function that takes an event and performs some processing. It doesn’t actually return anything. This is a special case of a subscription adapter that adapts an event to nothing. All of the work is done when the adapter “factory” is called. We call subscribers that don’t actually create anything “handlers”. There are special APIs for registering and calling them.
To register the subscriber above, we define a document-created event:
>>> class IDocumentCreated(interface.Interface): ... doc = interface.Attribute("The document that was created")>>> class DocumentCreated: ... interface.implements(IDocumentCreated) ... ... def __init__(self, doc): ... self.doc = doc
We’ll also change our handler definition to:
>>> def documentCreated(event): ... event.doc.created = datetime.datetime.utcnow()>>> documentCreated = component.adapter(IDocumentCreated)(documentCreated)
Note that in Python 2.4, this can be written:
>>> @component.adapter(IDocumentCreated) ... def documentCreated(event): ... event.doc.created = datetime.datetime.utcnow()
This marks the handler as an adapter of IDocumentCreated events.
Now we’ll register the handler [1]:
>>> component.provideHandler(documentCreated)
Now, if we can create an event and use the handle function to call handlers registered for the event:
>>> component.handle(DocumentCreated(doc)) >>> doc.created.__class__.__name__ 'datetime'
Events
The Component Architecture provides a way to dispatch events to event handlers. Event handlers are registered as subscribers a.k.a. handlers.
Before we can start we need to import zope.component.event to make the dispatching effective:
>>> import zope.component.event
Consider two event classes:
>>> class Event1(object): ... pass>>> class Event2(Event1): ... pass
Now consider two handlers for these event classes:
>>> called = []>>> import zope.component >>> @zope.component.adapter(Event1) ... def handler1(event): ... called.append(1)>>> @zope.component.adapter(Event2) ... def handler2(event): ... called.append(2)
We can register them with the Component Architecture:
>>> zope.component.provideHandler(handler1) >>> zope.component.provideHandler(handler2)
Now let’s go through the events. We’ll see that the handlers have been called accordingly:
>>> from zope.event import notify >>> notify(Event1()) >>> called [1]>>> del called[:] >>> notify(Event2()) >>> called.sort() >>> called [1, 2]
Object events
The objectEventNotify function is a subscriber to dispatch ObjectEvents to interested adapters.
First create an object class:
>>> class IUseless(zope.interface.Interface): ... """Useless object""">>> class UselessObject(object): ... """Useless object""" ... zope.interface.implements(IUseless)
Then create an event class:
>>> class IObjectThrownEvent(zope.component.interfaces.IObjectEvent): ... """An object has been thrown away""">>> class ObjectThrownEvent(zope.component.interfaces.ObjectEvent): ... """An object has been thrown away""" ... zope.interface.implements(IObjectThrownEvent)
Create an object and an event:
>>> hammer = UselessObject() >>> event = ObjectThrownEvent(hammer)
Then notify the event to the subscribers. Since the subscribers list is empty, nothing happens.
>>> zope.component.event.objectEventNotify(event)
Now create an handler for the event:
>>> events = [] >>> def record(*args): ... events.append(args)>>> zope.component.provideHandler(record, [IUseless, IObjectThrownEvent])
The event is notified to the subscriber:
>>> zope.component.event.objectEventNotify(event) >>> events == [(hammer, event)] True
Following test demonstrates how a subscriber can raise an exception to prevent an action.
>>> zope.component.provideHandler(zope.component.event.objectEventNotify)
Let’s create a container:
>>> class ToolBox(dict): ... def __delitem__(self, key): ... notify(ObjectThrownEvent(self[key])) ... return super(ToolBox,self).__delitem__(key)>>> container = ToolBox()
And put the object into the container:
>>> container['Red Hammer'] = hammer
Create an handler function that will raise an error when called:
>>> class Veto(Exception): ... pass>>> def callback(item, event): ... assert(item == event.object) ... raise Veto
Register the handler:
>>> zope.component.provideHandler(callback, [IUseless, IObjectThrownEvent])
Then if we try to remove the object, an ObjectThrownEvent is fired:
>>> del container['Red Hammer']
... # doctest: +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
raise Veto
Veto
Component-Management objects
Component-management objects provide a higher-level component-management API over the basic adapter-registration API provided by the zope.interface package. In particular, it provides:
utilities
support for computing adapters, rather than just looking up adapter factories.
management of registration comments
The zope.component.registry.Components class provides an implementation of zope.component.interfaces.IComponents that provides these features.
>>> from zope.component import registry
>>> from zope.component import tests
>>> components = registry.Components('comps')
As components are registered, events are generated. Let’s register an event subscriber, so we can see the events generated:
>>> import zope.event >>> def logevent(event): ... print event >>> zope.event.subscribers.append(logevent)
Utilities
You can register Utilities using registerUtility:
>>> components.registerUtility(tests.U1(1)) Registered event: UtilityRegistration(<Components comps>, I1, u'', 1, None, u'')
Here we didn’t specify an interface or name. An unnamed utility was registered for interface I1, since that is only interface implemented by the U1 class:
>>> components.getUtility(tests.I1) U1(1)
You can also register a utility using a factory instead of a utility instance:
>>> def factory(): ... return tests.U1(1) >>> components.registerUtility(factory=factory) Registered event: UtilityRegistration(<Components comps>, I1, u'', 1, <function factory at <SOME ADDRESS>>, u'')
If a component implements other than one interface or no interface, then an error will be raised:
>>> components.registerUtility(tests.U12(2)) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The utility doesn't provide a single interface and no provided interface was specified.>>> components.registerUtility(tests.A) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The utility doesn't provide a single interface and no provided interface was specified.
We can provide an interface if desired:
>>> components.registerUtility(tests.U12(2), tests.I2) Registered event: UtilityRegistration(<Components comps>, I2, u'', 2, None, u'')
and we can specify a name:
>>> components.registerUtility(tests.U12(3), tests.I2, u'three') Registered event: UtilityRegistration(<Components comps>, I2, u'three', 3, None, u'')>>> components.getUtility(tests.I2) U12(2)>>> components.getUtility(tests.I2, 'three') U12(3)
If you try to get a utility that doesn’t exist, you’ll get a component lookup error:
>>> components.getUtility(tests.I3) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... ComponentLookupError: (<InterfaceClass zope.component.tests.I3>, u'')
Unless you use queryUtility:
>>> components.queryUtility(tests.I3) >>> components.queryUtility(tests.I3, default=42) 42
You can get information about registered utilities with the registeredUtilities method:
>>> for registration in sorted(components.registeredUtilities()): ... print registration.provided, registration.name ... print registration.component, registration.info <InterfaceClass zope.component.tests.I1> U1(1) <InterfaceClass zope.component.tests.I2> U12(2) <InterfaceClass zope.component.tests.I2> three U12(3)
Duplicate registrations replace existing ones:
>>> components.registerUtility(tests.U1(4), info=u'use 4 now') Registered event: UtilityRegistration(<Components comps>, I1, u'', 4, None, u'use 4 now') >>> components.getUtility(tests.I1) U1(4)>>> for registration in sorted(components.registeredUtilities()): ... print registration.provided, registration.name ... print registration.component, registration.info <InterfaceClass zope.component.tests.I1> U1(4) use 4 now <InterfaceClass zope.component.tests.I2> U12(2) <InterfaceClass zope.component.tests.I2> three U12(3)
As shown in the this example, you can provide an “info” argumemnt when registering utilities. This provides extra documentation about the registration itself that is shown when listing registrations.
You can also unregister utilities:
>>> components.unregisterUtility(provided=tests.I1) Unregistered event: UtilityRegistration(<Components comps>, I1, u'', 4, None, u'use 4 now') True
A boolean is returned indicating whether anything changed:
>>> components.queryUtility(tests.I1) >>> for registration in sorted(components.registeredUtilities()): ... print registration.provided, registration.name ... print registration.component, registration.info <InterfaceClass zope.component.tests.I2> U12(2) <InterfaceClass zope.component.tests.I2> three U12(3)
When you unregister, you can specify a component. If the component doesn’t match the one registered, then nothing happens:
>>> u5 = tests.U1(5) >>> components.registerUtility(u5) Registered event: UtilityRegistration(<Components comps>, I1, u'', 5, None, u'') >>> components.unregisterUtility(tests.U1(6)) False >>> components.queryUtility(tests.I1) U1(5) >>> components.unregisterUtility(u5) Unregistered event: UtilityRegistration(<Components comps>, I1, u'', 5, None, u'') True >>> components.queryUtility(tests.I1)
You can get the name and utility for all of the utilities that provide an interface using getUtilitiesFor:
>>> sorted(components.getUtilitiesFor(tests.I2)) [(u'', U12(2)), (u'three', U12(3))]
getAllUtilitiesRegisteredFor is similar to getUtilitiesFor except that it includes utilities that are overridden. For example, we’ll register a utility that for an extending interface of I2:
>>> util = tests.U('ext')
>>> components.registerUtility(util, tests.I2e)
Registered event:
UtilityRegistration(<Components comps>, I2e, u'', ext, None, u'')
We don’t get the new utility for getUtilitiesFor:
>>> sorted(components.getUtilitiesFor(tests.I2)) [(u'', U12(2)), (u'three', U12(3))]
but we do get it from getAllUtilitiesRegisteredFor:
>>> sorted(map(str, components.getAllUtilitiesRegisteredFor(tests.I2))) ['U(ext)', 'U12(2)', 'U12(3)']
Removing a utility also makes it disappear from getUtilitiesFor:
>>> components.unregisterUtility(util, tests.I2e) Unregistered event: UtilityRegistration(<Components comps>, I2e, u'', ext, None, u'') True >>> list(components.getAllUtilitiesRegisteredFor(tests.I2e)) []
Adapters
You can register adapters with registerAdapter:
>>> components.registerAdapter(tests.A12_1) Registered event: AdapterRegistration(<Components comps>, [I1, I2], IA1, u'', A12_1, u'')
Here, we didn’t specify required interfaces, a provided interface, or a name. The required interfaces were determined from the factory s __component_adapts__ attribute and the provided interface was determined by introspecting what the factory implements.
>>> components.getMultiAdapter((tests.U1(6), tests.U12(7)), tests.IA1) A12_1(U1(6), U12(7))
If a factory implements more than one interface, an exception will be raised:
>>> components.registerAdapter(tests.A1_12) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.
Unless the provided interface is specified:
>>> components.registerAdapter(tests.A1_12, provided=tests.IA2) Registered event: AdapterRegistration(<Components comps>, [I1], IA2, u'', A1_12, u'')
If a factory doesn’t declare an implemented interface, an exception will be raised:
>>> components.registerAdapter(tests.A12_) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.
Unless the provided interface is specified:
>>> components.registerAdapter(tests.A12_, provided=tests.IA2) Registered event: AdapterRegistration(<Components comps>, [I1, I2], IA2, u'', A12_, u'')
The required interface needs to be specified in the registration if the factory doesn’t have a __component_adapts__ attribute:
>>> components.registerAdapter(tests.A_2) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't have a __component_adapts__ attribute and no required specifications were specified
Unless the required specifications specified:
>>> components.registerAdapter(tests.A_2, required=[tests.I3]) Registered event: AdapterRegistration(<Components comps>, [I3], IA2, u'', A_2, u'')
Classes can be specified in place of specifications, in which case the implementedBy specification for the class is used:
>>> components.registerAdapter(tests.A_3, required=[tests.U],
... info="Really class specific")
... # doctest: +NORMALIZE_WHITESPACE
Registered event:
AdapterRegistration(<Components comps>, [zope.component.tests.U], IA3, u'',
A_3, 'Really class specific')
We can see the adapters that have been registered using the registeredAdapters method:
>>> for registration in sorted(components.registeredAdapters()): ... print registration.required ... print registration.provided, registration.name ... print registration.factory, registration.info ... # doctest: +NORMALIZE_WHITESPACE (<InterfaceClass zope.component.tests.I1>, <InterfaceClass zope.component.tests.I2>) <InterfaceClass zope.component.tests.IA1> zope.component.tests.A12_1 (<InterfaceClass zope.component.tests.I1>, <InterfaceClass zope.component.tests.I2>) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A12_ (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A1_12 (<InterfaceClass zope.component.tests.I3>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A_2 (<implementedBy zope.component.tests.U>,) <InterfaceClass zope.component.tests.IA3> zope.component.tests.A_3 Really class specific
As with utilities, we can provide registration information when registering adapters.
If you try to fetch an adapter that isn’t registered, you’ll get a component-lookup error:
>>> components.getMultiAdapter((tests.U(8), ), tests.IA1)
... # doctest: +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
ComponentLookupError: ((U(8),),
<InterfaceClass zope.component.tests.IA1>, u'')
unless you use queryAdapter:
>>> components.queryMultiAdapter((tests.U(8), ), tests.IA1) >>> components.queryMultiAdapter((tests.U(8), ), tests.IA1, default=42) 42
When looking up an adapter for a single object, you can use the slightly simpler getAdapter and queryAdapter calls:
>>> components.getAdapter(tests.U1(9), tests.IA2) A1_12(U1(9))>>> components.queryAdapter(tests.U1(9), tests.IA2) A1_12(U1(9))>>> components.getAdapter(tests.U(8), tests.IA1) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... ComponentLookupError: (U(8), <InterfaceClass zope.component.tests.IA1>, u'')>>> components.queryAdapter(tests.U(8), tests.IA2) >>> components.queryAdapter(tests.U(8), tests.IA2, default=42) 42
You can unregister an adapter. If a factory is provided and if the rewuired and provided interfaces, can be infered, then they need not be provided:
>>> components.unregisterAdapter(tests.A12_1) Unregistered event: AdapterRegistration(<Components comps>, [I1, I2], IA1, u'', A12_1, u'') True>>> for registration in sorted(components.registeredAdapters()): ... print registration.required ... print registration.provided, registration.name ... print registration.factory, registration.info ... # doctest: +NORMALIZE_WHITESPACE (<InterfaceClass zope.component.tests.I1>, <InterfaceClass zope.component.tests.I2>) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A12_ (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A1_12 (<InterfaceClass zope.component.tests.I3>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A_2 (<implementedBy zope.component.tests.U>,) <InterfaceClass zope.component.tests.IA3> zope.component.tests.A_3 Really class specific
A boolean is returned indicating whether a change was made.
If a factory implements more than one interface, an exception will be raised:
>>> components.unregisterAdapter(tests.A1_12) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.
Unless the provided interface is specified:
>>> components.unregisterAdapter(tests.A1_12, provided=tests.IA2) Unregistered event: AdapterRegistration(<Components comps>, [I1], IA2, u'', A1_12, u'') True
If a factory doesn’t declare an implemented interface, an exception will be raised:
>>> components.unregisterAdapter(tests.A12_) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.
Unless the provided interface is specified:
>>> components.unregisterAdapter(tests.A12_, provided=tests.IA2) Unregistered event: AdapterRegistration(<Components comps>, [I1, I2], IA2, u'', A12_, u'') True
The required interface needs to be specified if the factory doesn’t have a __component_adapts__ attribute:
>>> components.unregisterAdapter(tests.A_2) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't have a __component_adapts__ attribute and no required specifications were specified>>> components.unregisterAdapter(tests.A_2, required=[tests.I3]) Unregistered event: AdapterRegistration(<Components comps>, [I3], IA2, u'', A_2, u'') True>>> for registration in sorted(components.registeredAdapters()): ... print registration.required ... print registration.provided, registration.name ... print registration.factory, registration.info ... # doctest: +NORMALIZE_WHITESPACE (<implementedBy zope.component.tests.U>,) <InterfaceClass zope.component.tests.IA3> zope.component.tests.A_3 Really class specific
If a factory is unregistered that is not registered, False is returned:
>>> components.unregisterAdapter(tests.A_2, required=[tests.I3]) False >>> components.unregisterAdapter(tests.A12_1, required=[tests.U]) False
The factory can be omitted, to unregister any factory that matches specified required and provided interfaces:
>>> components.unregisterAdapter(required=[tests.U], provided=tests.IA3) ... # doctest: +NORMALIZE_WHITESPACE Unregistered event: AdapterRegistration(<Components comps>, [zope.component.tests.U], IA3, u'', A_3, 'Really class specific') True>>> for registration in sorted(components.registeredAdapters()): ... print registration
Adapters can be named:
>>> components.registerAdapter(tests.A1_12, provided=tests.IA2, ... name=u'test') Registered event: AdapterRegistration(<Components comps>, [I1], IA2, u'test', A1_12, u'')>>> components.queryMultiAdapter((tests.U1(9), ), tests.IA2) >>> components.queryMultiAdapter((tests.U1(9), ), tests.IA2, name=u'test') A1_12(U1(9))>>> components.queryAdapter(tests.U1(9), tests.IA2) >>> components.queryAdapter(tests.U1(9), tests.IA2, name=u'test') A1_12(U1(9)) >>> components.getAdapter(tests.U1(9), tests.IA2, name=u'test') A1_12(U1(9))
It is possible to look up all of the adapters that provide an interface:
>>> components.registerAdapter(tests.A1_23, provided=tests.IA2, ... name=u'test 2') Registered event: AdapterRegistration(<Components comps>, [I1], IA2, u'test 2', A1_23, u'')>>> components.registerAdapter(tests.A1_12, provided=tests.IA2) Registered event: AdapterRegistration(<Components comps>, [I1], IA2, u'', A1_12, u'')>>> for name, adapter in sorted(components.getAdapters((tests.U1(9), ), ... tests.IA2)): ... print name, adapter A1_12(U1(9)) test A1_12(U1(9)) test 2 A1_23(U1(9))
getAdapters is most commonly used as the basis of menu systems.
If an adapter factory returns None, it is equivalent to there being no factory:
>>> components.registerAdapter(tests.noop, ... required=[tests.IA1], provided=tests.IA2, ... name=u'test noop') ... # doctest: +NORMALIZE_WHITESPACE Registered event: AdapterRegistration(<Components comps>, [IA1], IA2, u'test noop', noop, u'') >>> components.queryAdapter(tests.U1(9), tests.IA2, name=u'test noop')>>> components.registerAdapter(tests.A1_12, provided=tests.IA2) Registered event: AdapterRegistration(<Components comps>, [I1], IA2, u'', A1_12, u'')>>> for name, adapter in sorted(components.getAdapters((tests.U1(9), ), ... tests.IA2)): ... print name, adapter A1_12(U1(9)) test A1_12(U1(9)) test 2 A1_23(U1(9))>>> components.unregisterAdapter(tests.A1_12, provided=tests.IA2, ... name=u'test') Unregistered event: AdapterRegistration(<Components comps>, [I1], IA2, u'test', A1_12, u'') True >>> components.unregisterAdapter(tests.A1_12, provided=tests.IA2) Unregistered event: AdapterRegistration(<Components comps>, [I1], IA2, u'', A1_12, u'') True >>> for registration in sorted(components.registeredAdapters()): ... print registration.required ... print registration.provided, registration.name ... print registration.factory, registration.info ... # doctest: +NORMALIZE_WHITESPACE (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> test 2 zope.component.tests.A1_23 (<InterfaceClass zope.component.tests.IA1>,) <InterfaceClass zope.component.tests.IA2> test noop <function noop at 0xb79a1064>
Subscribers
Subscribers provide a way to get multiple adapters of a given type. In this regard, subscribers are like named adapters, except that there isn’t any concept of the most specific adapter for a given name.
Subscribers are registered by calling registerSubscriptionAdapter:
>>> components.registerSubscriptionAdapter(tests.A1_2) ... # doctest: +NORMALIZE_WHITESPACE Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A1_2, u'')>>> components.registerSubscriptionAdapter( ... tests.A1_12, provided=tests.IA2) ... # doctest: +NORMALIZE_WHITESPACE Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A1_12, u'')>>> components.registerSubscriptionAdapter( ... tests.A, [tests.I1], tests.IA2, ... info='a sample comment') ... # doctest: +NORMALIZE_WHITESPACE Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A, 'a sample comment')
The same rules, with regard to when required and provided interfaces have to be specified apply as with adapters:
>>> components.registerSubscriptionAdapter(tests.A1_12) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.>>> components.registerSubscriptionAdapter(tests.A) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.>>> components.registerSubscriptionAdapter(tests.A, required=[tests.IA1]) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.
Note that we provided the info argument as a keyword argument above. That’s because there is a name argument that’s reserved for future use. We can give a name, as long as it is an empty string:
>>> components.registerSubscriptionAdapter( ... tests.A, [tests.I1], tests.IA2, u'', 'a sample comment') ... # doctest: +NORMALIZE_WHITESPACE Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A, 'a sample comment')>>> components.registerSubscriptionAdapter( ... tests.A, [tests.I1], tests.IA2, u'oops', 'a sample comment') Traceback (most recent call last): ... TypeError: Named subscribers are not yet supported
Subscribers are looked up using the subscribers method:
>>> for s in components.subscribers((tests.U1(1), ), tests.IA2): ... print s A1_2(U1(1)) A1_12(U1(1)) A(U1(1),) A(U1(1),)
Note that, because we created multiple subscriptions for A, we got multiple subscriber instances.
As with normal adapters, if a factory returns None, the result is skipped:
>>> components.registerSubscriptionAdapter( ... tests.noop, [tests.I1], tests.IA2) Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', noop, u'')>>> for s in components.subscribers((tests.U1(1), ), tests.IA2): ... print s A1_2(U1(1)) A1_12(U1(1)) A(U1(1),) A(U1(1),)
We can get registration information for subscriptions:
>>> for registration in sorted( ... components.registeredSubscriptionAdapters()): ... print registration.required ... print registration.provided, registration.name ... print registration.factory, registration.info (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A a sample comment (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A a sample comment (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A1_12 (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A1_2 (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> <function noop at 0xb796ff7c>
We can also unregister subscriptions in much the same way we can for adapters:
>>> components.unregisterSubscriptionAdapter(tests.A1_2) ... # doctest: +NORMALIZE_WHITESPACE Unregistered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A1_2, '') True>>> for s in components.subscribers((tests.U1(1), ), tests.IA2): ... print s A1_12(U1(1)) A(U1(1),) A(U1(1),)>>> for registration in sorted( ... components.registeredSubscriptionAdapters()): ... print registration.required ... print registration.provided, registration.name ... print registration.factory, registration.info (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A a sample comment (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A a sample comment (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A1_12 (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> <function noop at 0xb796ff7c>>>> components.unregisterSubscriptionAdapter( ... tests.A, [tests.I1], tests.IA2) Unregistered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A, '') True>>> for s in components.subscribers((tests.U1(1), ), tests.IA2): ... print s A1_12(U1(1))>>> for registration in sorted( ... components.registeredSubscriptionAdapters()): ... print registration.required ... print registration.provided, registration.name ... print registration.factory, registration.info (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> zope.component.tests.A1_12 (<InterfaceClass zope.component.tests.I1>,) <InterfaceClass zope.component.tests.IA2> <function noop at 0xb796ff7c>
Note here that both registrations for A were removed.
If we omit the factory, we must specify the required and provided interfaces:
>>> components.unregisterSubscriptionAdapter(required=[tests.I1]) Traceback (most recent call last): ... TypeError: Must specify one of factory and provided>>> components.unregisterSubscriptionAdapter(provided=tests.IA2) Traceback (most recent call last): ... TypeError: Must specify one of factory and required>>> components.unregisterSubscriptionAdapter( ... required=[tests.I1], provided=tests.IA2) Unregistered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', None, '') True>>> for s in components.subscribers((tests.U1(1), ), tests.IA2): ... print s>>> for registration in sorted( ... components.registeredSubscriptionAdapters()): ... print registration.factory
As when registering, an error is raised if the registration information can’t be determined from the factory and isn’t specified:
>>> components.unregisterSubscriptionAdapter(tests.A1_12) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.>>> components.unregisterSubscriptionAdapter(tests.A) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.>>> components.unregisterSubscriptionAdapter(tests.A, required=[tests.IA1]) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't implement a single interface and no provided interface was specified.
If you unregister something that’s not registered, nothing will be changed and False will be returned:
>>> components.unregisterSubscriptionAdapter( ... required=[tests.I1], provided=tests.IA2) False
Handlers
Handlers are used when you want to perform some function in response to an event. Handlers aren’t expected to return anything when called and are not registered to provide any interface.
>>> from zope import component >>> @component.adapter(tests.I1) ... def handle1(x): ... print 'handle1', x>>> components.registerHandler(handle1, info="First handler") ... # doctest: +NORMALIZE_WHITESPACE Registered event: HandlerRegistration(<Components comps>, [I1], u'', handle1, 'First handler') >>> components.handle(tests.U1(1)) handle1 U1(1)>>> @component.adapter(tests.I1, tests.I2) ... def handle12(x, y): ... print 'handle12', x, y>>> components.registerHandler(handle12) Registered event: HandlerRegistration(<Components comps>, [I1, I2], u'', handle12, u'') >>> components.handle(tests.U1(1), tests.U12(2)) handle12 U1(1) U12(2)
If a handler doesn’t document interfaces it handles, then the required interfaces must be specified:
>>> def handle(*objects): ... print 'handle', objects>>> components.registerHandler(handle) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't have a __component_adapts__ attribute and no required specifications were specified>>> components.registerHandler(handle, required=[tests.I1], ... info="a comment") Registered event: HandlerRegistration(<Components comps>, [I1], u'', handle, 'a comment')
Handlers can also be registered for classes:
>>> components.registerHandler(handle, required=[tests.U], ... info="handle a class") ... # doctest: +NORMALIZE_WHITESPACE Registered event: HandlerRegistration(<Components comps>, [zope.component.tests.U], u'', handle, 'handle a class')>>> components.handle(tests.U1(1)) handle (U1(1),) handle1 U1(1) handle (U1(1),)
We can list the handler registrations:
>>> for registration in components.registeredHandlers(): ... print registration.required ... print registration.handler, registration.info ... # doctest: +NORMALIZE_WHITESPACE (<InterfaceClass zope.component.tests.I1>,) <function handle1 at 0xb78f5bfc> First handler (<InterfaceClass zope.component.tests.I1>, <InterfaceClass zope.component.tests.I2>) <function handle12 at 0xb78f5c34> (<InterfaceClass zope.component.tests.I1>,) <function handle at 0xb78f5ca4> a comment (<implementedBy zope.component.tests.U>,) <function handle at 0xb78f5ca4> handle a class
and we can unregister handlers:
>>> components.unregisterHandler(required=[tests.U]) ... # doctest: +NORMALIZE_WHITESPACE Unregistered event: HandlerRegistration(<Components comps>, [zope.component.tests.U], u'', None, '') True>>> for registration in components.registeredHandlers(): ... print registration.required ... print registration.handler, registration.info ... # doctest: +NORMALIZE_WHITESPACE (<InterfaceClass zope.component.tests.I1>,) <function handle1 at 0xb78f5bfc> First handler (<InterfaceClass zope.component.tests.I1>, <InterfaceClass zope.component.tests.I2>) <function handle12 at 0xb78f5c34> (<InterfaceClass zope.component.tests.I1>,) <function handle at 0xb78f5ca4> a comment>>> components.unregisterHandler(handle12) Unregistered event: HandlerRegistration(<Components comps>, [I1, I2], u'', handle12, '') True>>> for registration in components.registeredHandlers(): ... print registration.required ... print registration.handler, registration.info (<InterfaceClass zope.component.tests.I1>,) <function handle1 at 0xb78f5bfc> First handler (<InterfaceClass zope.component.tests.I1>,) <function handle at 0xb78f5ca4> a comment>>> components.unregisterHandler(handle12) False>>> components.unregisterHandler() Traceback (most recent call last): ... TypeError: Must specify one of factory and required>>> components.registerHandler(handle) ... # doctest: +NORMALIZE_WHITESPACE Traceback (most recent call last): ... TypeError: The adapter factory doesn't have a __component_adapts__ attribute and no required specifications were specified
Extending
Component-management objects can extend other component-management objects.
>>> c1 = registry.Components('1') >>> c1.__bases__ ()>>> c2 = registry.Components('2', (c1, )) >>> c2.__bases__ == (c1, ) True>>> c1.registerUtility(tests.U1(1)) Registered event: UtilityRegistration(<Components 1>, I1, u'', 1, None, u'')>>> c1.queryUtility(tests.I1) U1(1) >>> c2.queryUtility(tests.I1) U1(1) >>> c1.registerUtility(tests.U1(2)) Registered event: UtilityRegistration(<Components 1>, I1, u'', 2, None, u'')>>> c2.queryUtility(tests.I1) U1(2)
We can use multiple inheritence:
>>> c3 = registry.Components('3', (c1, )) >>> c4 = registry.Components('4', (c2, c3)) >>> c4.queryUtility(tests.I1) U1(2)>>> c1.registerUtility(tests.U12(1), tests.I2) Registered event: UtilityRegistration(<Components 1>, I2, u'', 1, None, u'')>>> c4.queryUtility(tests.I2) U12(1)>>> c3.registerUtility(tests.U12(3), tests.I2) Registered event: UtilityRegistration(<Components 3>, I2, u'', 3, None, u'') >>> c4.queryUtility(tests.I2) U12(3)>>> c1.registerHandler(handle1, info="First handler") Registered event: HandlerRegistration(<Components 1>, [I1], u'', handle1, 'First handler')>>> c2.registerHandler(handle, required=[tests.U]) ... # doctest: +NORMALIZE_WHITESPACE Registered event: HandlerRegistration(<Components 2>, [zope.component.tests.U], u'', handle, u'')>>> @component.adapter(tests.I1) ... def handle3(x): ... print 'handle3', x >>> c3.registerHandler(handle3) Registered event: HandlerRegistration(<Components 3>, [I1], u'', handle3, u'')>>> @component.adapter(tests.I1) ... def handle4(x): ... print 'handle4', x >>> c4.registerHandler(handle4) Registered event: HandlerRegistration(<Components 4>, [I1], u'', handle4, u'')>>> c4.handle(tests.U1(1)) handle1 U1(1) handle3 U1(1) handle (U1(1),) handle4 U1(1)
Redispatch of registration events
Some handlers are available that, if registered, redispatch registration events to the objects being registered. They depend on being dispatched to by the object-event dispatcher:
>>> from zope import component
>>> import zope.component.event
>>> zope.component.getGlobalSiteManager().registerHandler(
... zope.component.event.objectEventNotify)
... # doctest: +NORMALIZE_WHITESPACE
Registered event:
HandlerRegistration(<BaseGlobalComponents base>,
[IObjectEvent], u'', objectEventNotify, u'')
To see this, we’ll first register a multi-handler to show is when handlers are called on 2 objects:
>>> @zope.component.adapter(None, None)
... def double_handler(o1, o2):
... print 'Double dispatch:'
... print ' ', o1
... print ' ', o2
>>> zope.component.getGlobalSiteManager().registerHandler(double_handler)
... # doctest: +NORMALIZE_WHITESPACE
Double dispatch:
HandlerRegistration(<BaseGlobalComponents base>,
[Interface, Interface], u'', double_handler, u'')
Registered event:
HandlerRegistration(<BaseGlobalComponents base>,
[Interface, Interface], u'', double_handler, u'')
Registered event:
HandlerRegistration(<BaseGlobalComponents base>,
[Interface, Interface], u'', double_handler, u'')
In the example above, the double_handler reported it’s own registration. :)
Now we’ll register our handlers:
>>> zope.component.getGlobalSiteManager().registerHandler( ... registry.dispatchUtilityRegistrationEvent) ... # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS Double dispatch: ...>>> zope.component.getGlobalSiteManager().registerHandler( ... registry.dispatchAdapterRegistrationEvent) ... # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS Double dispatch: ...>>> zope.component.getGlobalSiteManager().registerHandler( ... registry.dispatchSubscriptionAdapterRegistrationEvent) ... # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS Double dispatch: ...>>> zope.component.getGlobalSiteManager().registerHandler( ... registry.dispatchHandlerRegistrationEvent) ... # doctest: +NORMALIZE_WHITESPACE Double dispatch: HandlerRegistration(<BaseGlobalComponents base>, [IHandlerRegistration, IRegistrationEvent], u'', dispatchHandlerRegistrationEvent, u'') Registered event: HandlerRegistration(<BaseGlobalComponents base>, [IHandlerRegistration, IRegistrationEvent], u'', dispatchHandlerRegistrationEvent, u'') Double dispatch: <function dispatchHandlerRegistrationEvent at 0xb799f72c> Registered event: HandlerRegistration(<BaseGlobalComponents base>, [IHandlerRegistration, IRegistrationEvent], u'', dispatchHandlerRegistrationEvent, u'') Registered event: HandlerRegistration(<BaseGlobalComponents base>, [IHandlerRegistration, IRegistrationEvent], u'', dispatchHandlerRegistrationEvent, u'')
In the last example above, we can see that the registration of dispatchHandlerRegistrationEvent was handled by dispatchHandlerRegistrationEvent and redispatched. This can be seen in the second double-dispatch output, where the first argument is the object being registered, which is dispatchHandlerRegistrationEvent.
If we change some other registrations, we can the double dispatch taking place:
>>> components.registerUtility(u5) ... # doctest: +NORMALIZE_WHITESPACE Double dispatch: UtilityRegistration(<Components comps>, I1, u'', 5, None, u'') Registered event: UtilityRegistration(<Components comps>, I1, u'', 5, None, u'') Double dispatch: U1(5) Registered event: UtilityRegistration(<Components comps>, I1, u'', 5, None, u'') Registered event: UtilityRegistration(<Components comps>, I1, u'', 5, None, u'')>>> components.registerAdapter(tests.A12_1) ... # doctest: +NORMALIZE_WHITESPACE Double dispatch: AdapterRegistration(<Components comps>, [I1, I2], IA1, u'', A12_1, u'') Registered event: AdapterRegistration(<Components comps>, [I1, I2], IA1, u'', A12_1, u'') Double dispatch: zope.component.tests.A12_1 Registered event: AdapterRegistration(<Components comps>, [I1, I2], IA1, u'', A12_1, u'') Registered event: AdapterRegistration(<Components comps>, [I1, I2], IA1, u'', A12_1, u'')>>> components.registerSubscriptionAdapter(tests.A1_2) ... # doctest: +NORMALIZE_WHITESPACE Double dispatch: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A1_2, u'') Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A1_2, u'') Double dispatch: zope.component.tests.A1_2 Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A1_2, u'') Registered event: SubscriptionRegistration(<Components comps>, [I1], IA2, u'', A1_2, u'')
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