subscriber ZCML directive configures an :term:`subscriber`
callable to listen for events broadcast by the Pyramid web
- The class or :term:`interface` that you are subscribing the listener for,
e.g. :class:`pyramid.events.NewRequest`. Registering a subscriber for a
specific class or interface limits the event types that the subscriber
will receive to those specified by the interface or class. Default:
zope.interface.Interface(implying any event type).
- A :term:`dotted Python name` which references an event handler
callable. The callable should accept a single argument:
event. The return value of the callable is ignored.
You can also register an event listener by using the :meth:`pyramid.config.Configurator.add_subscriber` method.
See also :ref:`events_chapter`.