from webob import Response as WebobResponse
from functools import update_wrapper
from zope.interface import Interface
from pyramid.interfaces import IResponse, ITraverser, IResourceURL
from pyramid.util import takes_one_arg
from pyramid.config.actions import action_method
class AdaptersConfiguratorMixin(object):
@action_method
def add_subscriber(self, subscriber, iface=None, **predicates):
"""Add an event :term:`subscriber` for the event stream
implied by the supplied ``iface`` interface.
The ``subscriber`` argument represents a callable object (or a
:term:`dotted Python name` which identifies a callable); it will be
called with a single object ``event`` whenever :app:`Pyramid` emits
an :term:`event` associated with the ``iface``, which may be an
:term:`interface` or a class or a :term:`dotted Python name` to a
global object representing an interface or a class.
Using the default ``iface`` value, ``None`` will cause the subscriber
to be registered for all event types. See :ref:`events_chapter` for
more information about events and subscribers.
Any number of predicate keyword arguments may be passed in
``**predicates``. Each predicate named will narrow the set of
circumstances in which the subscriber will be invoked. Each named
predicate must have been registered via
:meth:`pyramid.config.Configurator.add_subscriber_predicate` before it
can be used. See :ref:`subscriber_predicates` for more information.
.. versionadded:: 1.4
The ``**predicates`` argument.
"""
dotted = self.maybe_dotted
subscriber, iface = dotted(subscriber), dotted(iface)
if iface is None:
iface = (Interface,)
if not isinstance(iface, (tuple, list)):
iface = (iface,)
def register():
predlist = self.get_predlist('subscriber')
order, preds, phash = predlist.make(self, **predicates)
derived_predicates = [self._derive_predicate(p) for p in preds]
derived_subscriber = self._derive_subscriber(
subscriber, derived_predicates
)
intr.update(
{
'phash': phash,
'order': order,
'predicates': preds,
'derived_predicates': derived_predicates,
'derived_subscriber': derived_subscriber,
}
)
self.registry.registerHandler(derived_subscriber, iface)
intr = self.introspectable(
'subscribers',
id(subscriber),
self.object_description(subscriber),
'subscriber',
)
intr['subscriber'] = subscriber
intr['interfaces'] = iface
self.action(None, register, introspectables=(intr,))
return subscriber
def _derive_predicate(self, predicate):
derived_predicate = predicate
if eventonly(predicate):
def derived_predicate(*arg):
return predicate(arg[0])
# seems pointless to try to fix __doc__, __module__, etc as
# predicate will invariably be an instance
return derived_predicate
def _derive_subscriber(self, subscriber, predicates):
derived_subscriber = subscriber
if eventonly(subscriber):
def derived_subscriber(*arg):
return subscriber(arg[0])
if hasattr(subscriber, '__name__'):
update_wrapper(derived_subscriber, subscriber)
if not predicates:
return derived_subscriber
def subscriber_wrapper(*arg):
# We need to accept *arg and pass it along because zope subscribers
# are designed awkwardly. Notification via
# registry.adapter.subscribers will always call an associated
# subscriber with all of the objects involved in the subscription
# lookup, despite the fact that the event sender always has the
# option to attach those objects to the event object itself, and
# almost always does.
#
# The "eventonly" jazz sprinkled in this function and related
# functions allows users to define subscribers and predicates which
# accept only an event argument without needing to accept the rest
# of the adaptation arguments. Had I been smart enough early on to
# use .subscriptions to find the subscriber functions in order to
# call them manually with a single "event" argument instead of
# relying on .subscribers to both find and call them implicitly
# with all args, the eventonly hack would not have been required.
# At this point, though, using .subscriptions and manual execution
# is not possible without badly breaking backwards compatibility.
if all((predicate(*arg) for predicate in predicates)):
return derived_subscriber(*arg)
if hasattr(subscriber, '__name__'):
update_wrapper(subscriber_wrapper, subscriber)
return subscriber_wrapper
@action_method
def add_subscriber_predicate(
self, name, factory, weighs_more_than=None, weighs_less_than=None
):
"""
.. versionadded:: 1.4
Adds a subscriber predicate factory. The associated subscriber
predicate can later be named as a keyword argument to
:meth:`pyramid.config.Configurator.add_subscriber` in the
``**predicates`` anonymous keyword argument dictionary.
``name`` should be the name of the predicate. It must be a valid
Python identifier (it will be used as a ``**predicates`` keyword
argument to :meth:`~pyramid.config.Configurator.add_subscriber`).
``factory`` should be a :term:`predicate factory` or :term:`dotted
Python name` which refers to a predicate factory.
See :ref:`subscriber_predicates` for more information.
"""
self._add_predicate(
'subscriber',
name,
factory,
weighs_more_than=weighs_more_than,
weighs_less_than=weighs_less_than,
)
@action_method
def add_response_adapter(self, adapter, type_or_iface):
"""When an object of type (or interface) ``type_or_iface`` is
returned from a view callable, Pyramid will use the adapter
``adapter`` to convert it into an object which implements the
:class:`pyramid.interfaces.IResponse` interface. If ``adapter`` is
None, an object returned of type (or interface) ``type_or_iface``
will itself be used as a response object.
``adapter`` and ``type_or_interface`` may be Python objects or
strings representing dotted names to importable Python global
objects.
See :ref:`using_iresponse` for more information."""
adapter = self.maybe_dotted(adapter)
type_or_iface = self.maybe_dotted(type_or_iface)
def register():
reg = self.registry
if adapter is None:
reg.registerSelfAdapter((type_or_iface,), IResponse)
else:
reg.registerAdapter(adapter, (type_or_iface,), IResponse)
discriminator = (IResponse, type_or_iface)
intr = self.introspectable(
'response adapters',
discriminator,
self.object_description(adapter),
'response adapter',
)
intr['adapter'] = adapter
intr['type'] = type_or_iface
self.action(discriminator, register, introspectables=(intr,))
def add_default_response_adapters(self):
# cope with WebOb response objects that aren't decorated with IResponse
self.add_response_adapter(None, WebobResponse)
@action_method
def add_traverser(self, adapter, iface=None):
"""
The superdefault :term:`traversal` algorithm that :app:`Pyramid` uses
is explained in :ref:`traversal_algorithm`. Though it is rarely
necessary, this default algorithm can be swapped out selectively for
a different traversal pattern via configuration. The section
entitled :ref:`changing_the_traverser` details how to create a
traverser class.
For example, to override the superdefault traverser used by Pyramid,
you might do something like this:
.. code-block:: python
from myapp.traversal import MyCustomTraverser
config.add_traverser(MyCustomTraverser)
This would cause the Pyramid superdefault traverser to never be used;
instead all traversal would be done using your ``MyCustomTraverser``
class, no matter which object was returned by the :term:`root
factory` of this application. Note that we passed no arguments to
the ``iface`` keyword parameter. The default value of ``iface``,
``None`` represents that the registered traverser should be used when
no other more specific traverser is available for the object returned
by the root factory.
However, more than one traversal algorithm can be active at the same
time. The traverser used can depend on the result of the :term:`root
factory`. For instance, if your root factory returns more than one
type of object conditionally, you could claim that an alternate
traverser adapter should be used against one particular class or
interface returned by that root factory. When the root factory
returned an object that implemented that class or interface, a custom
traverser would be used. Otherwise, the default traverser would be
used. The ``iface`` argument represents the class of the object that
the root factory might return or an :term:`interface` that the object
might implement.
To use a particular traverser only when the root factory returns a
particular class:
.. code-block:: python
config.add_traverser(MyCustomTraverser, MyRootClass)
When more than one traverser is active, the "most specific" traverser
will be used (the one that matches the class or interface of the
value returned by the root factory most closely).
Note that either ``adapter`` or ``iface`` can be a :term:`dotted
Python name` or a Python object.
See :ref:`changing_the_traverser` for more information.
"""
iface = self.maybe_dotted(iface)
adapter = self.maybe_dotted(adapter)
def register(iface=iface):
if iface is None:
iface = Interface
self.registry.registerAdapter(adapter, (iface,), ITraverser)
discriminator = ('traverser', iface)
intr = self.introspectable(
'traversers',
discriminator,
'traverser for %r' % iface,
'traverser',
)
intr['adapter'] = adapter
intr['iface'] = iface
self.action(discriminator, register, introspectables=(intr,))
@action_method
def add_resource_url_adapter(self, adapter, resource_iface=None):
"""
.. versionadded:: 1.3
When you add a traverser as described in
:ref:`changing_the_traverser`, it's convenient to continue to use the
:meth:`pyramid.request.Request.resource_url` API. However, since the
way traversal is done may have been modified, the URLs that
``resource_url`` generates by default may be incorrect when resources
are returned by a custom traverser.
If you've added a traverser, you can change how
:meth:`~pyramid.request.Request.resource_url` generates a URL for a
specific type of resource by calling this method.
The ``adapter`` argument represents a class that implements the
:class:`~pyramid.interfaces.IResourceURL` interface. The class
constructor should accept two arguments in its constructor (the
resource and the request) and the resulting instance should provide
the attributes detailed in that interface (``virtual_path`` and
``physical_path``, in particular).
The ``resource_iface`` argument represents a class or interface that
the resource should possess for this url adapter to be used when
:meth:`pyramid.request.Request.resource_url` looks up a resource url
adapter. If ``resource_iface`` is not passed, or it is passed as
``None``, the url adapter will be used for every type of resource.
See :ref:`changing_resource_url` for more information.
"""
adapter = self.maybe_dotted(adapter)
resource_iface = self.maybe_dotted(resource_iface)
def register(resource_iface=resource_iface):
if resource_iface is None:
resource_iface = Interface
self.registry.registerAdapter(
adapter, (resource_iface, Interface), IResourceURL
)
discriminator = ('resource url adapter', resource_iface)
intr = self.introspectable(
'resource url adapters',
discriminator,
'resource url adapter for resource iface %r' % resource_iface,
'resource url adapter',
)
intr['adapter'] = adapter
intr['resource_iface'] = resource_iface
self.action(discriminator, register, introspectables=(intr,))
def eventonly(callee):
return takes_one_arg(callee, argname='event')
