444 lines
14 KiB
Python
444 lines
14 KiB
Python
|
# -*- test-case-name: twisted.python.test.test_components -*-
|
||
|
|
# Copyright (c) Twisted Matrix Laboratories.
|
||
|
|
# See LICENSE for details.
|
||
|
|
|
||
|
|
|
||
|
|
"""
|
||
|
|
Component architecture for Twisted, based on Zope3 components.
|
||
|
|
|
||
|
|
Using the Zope3 API directly is strongly recommended. Everything
|
||
|
|
you need is in the top-level of the zope.interface package, e.g.::
|
||
|
|
|
||
|
|
from zope.interface import Interface, implements
|
||
|
|
|
||
|
|
class IFoo(Interface):
|
||
|
|
pass
|
||
|
|
|
||
|
|
class Foo:
|
||
|
|
implements(IFoo)
|
||
|
|
|
||
|
|
print IFoo.implementedBy(Foo) # True
|
||
|
|
print IFoo.providedBy(Foo()) # True
|
||
|
|
|
||
|
|
L{twisted.python.components.registerAdapter} from this module may be used to
|
||
|
|
add to Twisted's global adapter registry.
|
||
|
|
|
||
|
|
L{twisted.python.components.proxyForInterface} is a factory for classes
|
||
|
|
which allow access to only the parts of another class defined by a specified
|
||
|
|
interface.
|
||
|
|
"""
|
||
|
|
|
||
|
|
from __future__ import division, absolute_import
|
||
|
|
|
||
|
|
# zope3 imports
|
||
|
|
from zope.interface import interface, declarations
|
||
|
|
from zope.interface.adapter import AdapterRegistry
|
||
|
|
|
||
|
|
# twisted imports
|
||
|
|
from twisted.python.compat import NativeStringIO
|
||
|
|
from twisted.python import reflect
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
# Twisted's global adapter registry
|
||
|
|
globalRegistry = AdapterRegistry()
|
||
|
|
|
||
|
|
# Attribute that registerAdapter looks at. Is this supposed to be public?
|
||
|
|
ALLOW_DUPLICATES = 0
|
||
|
|
|
||
|
|
# Define a function to find the registered adapter factory, using either a
|
||
|
|
# version of Zope Interface which has the `registered' method or an older
|
||
|
|
# version which does not.
|
||
|
|
if getattr(AdapterRegistry, 'registered', None) is None:
|
||
|
|
def _registered(registry, required, provided):
|
||
|
|
"""
|
||
|
|
Return the adapter factory for the given parameters in the given
|
||
|
|
registry, or None if there is not one.
|
||
|
|
"""
|
||
|
|
return registry.get(required).selfImplied.get(provided, {}).get('')
|
||
|
|
else:
|
||
|
|
def _registered(registry, required, provided):
|
||
|
|
"""
|
||
|
|
Return the adapter factory for the given parameters in the given
|
||
|
|
registry, or None if there is not one.
|
||
|
|
"""
|
||
|
|
return registry.registered([required], provided)
|
||
|
|
|
||
|
|
|
||
|
|
def registerAdapter(adapterFactory, origInterface, *interfaceClasses):
|
||
|
|
"""Register an adapter class.
|
||
|
|
|
||
|
|
An adapter class is expected to implement the given interface, by
|
||
|
|
adapting instances implementing 'origInterface'. An adapter class's
|
||
|
|
__init__ method should accept one parameter, an instance implementing
|
||
|
|
'origInterface'.
|
||
|
|
"""
|
||
|
|
self = globalRegistry
|
||
|
|
assert interfaceClasses, "You need to pass an Interface"
|
||
|
|
global ALLOW_DUPLICATES
|
||
|
|
|
||
|
|
# deal with class->interface adapters:
|
||
|
|
if not isinstance(origInterface, interface.InterfaceClass):
|
||
|
|
origInterface = declarations.implementedBy(origInterface)
|
||
|
|
|
||
|
|
for interfaceClass in interfaceClasses:
|
||
|
|
factory = _registered(self, origInterface, interfaceClass)
|
||
|
|
if factory is not None and not ALLOW_DUPLICATES:
|
||
|
|
raise ValueError("an adapter (%s) was already registered." % (factory, ))
|
||
|
|
for interfaceClass in interfaceClasses:
|
||
|
|
self.register([origInterface], interfaceClass, '', adapterFactory)
|
||
|
|
|
||
|
|
|
||
|
|
def getAdapterFactory(fromInterface, toInterface, default):
|
||
|
|
"""Return registered adapter for a given class and interface.
|
||
|
|
|
||
|
|
Note that is tied to the *Twisted* global registry, and will
|
||
|
|
thus not find adapters registered elsewhere.
|
||
|
|
"""
|
||
|
|
self = globalRegistry
|
||
|
|
if not isinstance(fromInterface, interface.InterfaceClass):
|
||
|
|
fromInterface = declarations.implementedBy(fromInterface)
|
||
|
|
factory = self.lookup1(fromInterface, toInterface)
|
||
|
|
if factory is None:
|
||
|
|
factory = default
|
||
|
|
return factory
|
||
|
|
|
||
|
|
|
||
|
|
def _addHook(registry):
|
||
|
|
"""
|
||
|
|
Add an adapter hook which will attempt to look up adapters in the given
|
||
|
|
registry.
|
||
|
|
|
||
|
|
@type registry: L{zope.interface.adapter.AdapterRegistry}
|
||
|
|
|
||
|
|
@return: The hook which was added, for later use with L{_removeHook}.
|
||
|
|
"""
|
||
|
|
lookup = registry.lookup1
|
||
|
|
def _hook(iface, ob):
|
||
|
|
factory = lookup(declarations.providedBy(ob), iface)
|
||
|
|
if factory is None:
|
||
|
|
return None
|
||
|
|
else:
|
||
|
|
return factory(ob)
|
||
|
|
interface.adapter_hooks.append(_hook)
|
||
|
|
return _hook
|
||
|
|
|
||
|
|
|
||
|
|
def _removeHook(hook):
|
||
|
|
"""
|
||
|
|
Remove a previously added adapter hook.
|
||
|
|
|
||
|
|
@param hook: An object previously returned by a call to L{_addHook}. This
|
||
|
|
will be removed from the list of adapter hooks.
|
||
|
|
"""
|
||
|
|
interface.adapter_hooks.remove(hook)
|
||
|
|
|
||
|
|
# add global adapter lookup hook for our newly created registry
|
||
|
|
_addHook(globalRegistry)
|
||
|
|
|
||
|
|
|
||
|
|
def getRegistry():
|
||
|
|
"""Returns the Twisted global
|
||
|
|
C{zope.interface.adapter.AdapterRegistry} instance.
|
||
|
|
"""
|
||
|
|
return globalRegistry
|
||
|
|
|
||
|
|
# FIXME: deprecate attribute somehow?
|
||
|
|
CannotAdapt = TypeError
|
||
|
|
|
||
|
|
class Adapter:
|
||
|
|
"""I am the default implementation of an Adapter for some interface.
|
||
|
|
|
||
|
|
This docstring contains a limerick, by popular demand::
|
||
|
|
|
||
|
|
Subclassing made Zope and TR
|
||
|
|
much harder to work with by far.
|
||
|
|
So before you inherit,
|
||
|
|
be sure to declare it
|
||
|
|
Adapter, not PyObject*
|
||
|
|
|
||
|
|
@cvar temporaryAdapter: If this is True, the adapter will not be
|
||
|
|
persisted on the Componentized.
|
||
|
|
@cvar multiComponent: If this adapter is persistent, should it be
|
||
|
|
automatically registered for all appropriate interfaces.
|
||
|
|
"""
|
||
|
|
|
||
|
|
# These attributes are used with Componentized.
|
||
|
|
|
||
|
|
temporaryAdapter = 0
|
||
|
|
multiComponent = 1
|
||
|
|
|
||
|
|
def __init__(self, original):
|
||
|
|
"""Set my 'original' attribute to be the object I am adapting.
|
||
|
|
"""
|
||
|
|
self.original = original
|
||
|
|
|
||
|
|
def __conform__(self, interface):
|
||
|
|
"""
|
||
|
|
I forward __conform__ to self.original if it has it, otherwise I
|
||
|
|
simply return None.
|
||
|
|
"""
|
||
|
|
if hasattr(self.original, "__conform__"):
|
||
|
|
return self.original.__conform__(interface)
|
||
|
|
return None
|
||
|
|
|
||
|
|
def isuper(self, iface, adapter):
|
||
|
|
"""
|
||
|
|
Forward isuper to self.original
|
||
|
|
"""
|
||
|
|
return self.original.isuper(iface, adapter)
|
||
|
|
|
||
|
|
|
||
|
|
class Componentized:
|
||
|
|
"""I am a mixin to allow you to be adapted in various ways persistently.
|
||
|
|
|
||
|
|
I define a list of persistent adapters. This is to allow adapter classes
|
||
|
|
to store system-specific state, and initialized on demand. The
|
||
|
|
getComponent method implements this. You must also register adapters for
|
||
|
|
this class for the interfaces that you wish to pass to getComponent.
|
||
|
|
|
||
|
|
Many other classes and utilities listed here are present in Zope3; this one
|
||
|
|
is specific to Twisted.
|
||
|
|
"""
|
||
|
|
|
||
|
|
persistenceVersion = 1
|
||
|
|
|
||
|
|
def __init__(self):
|
||
|
|
self._adapterCache = {}
|
||
|
|
|
||
|
|
def locateAdapterClass(self, klass, interfaceClass, default):
|
||
|
|
return getAdapterFactory(klass, interfaceClass, default)
|
||
|
|
|
||
|
|
def setAdapter(self, interfaceClass, adapterClass):
|
||
|
|
"""
|
||
|
|
Cache a provider for the given interface, by adapting C{self} using
|
||
|
|
the given adapter class.
|
||
|
|
"""
|
||
|
|
self.setComponent(interfaceClass, adapterClass(self))
|
||
|
|
|
||
|
|
def addAdapter(self, adapterClass, ignoreClass=0):
|
||
|
|
"""Utility method that calls addComponent. I take an adapter class and
|
||
|
|
instantiate it with myself as the first argument.
|
||
|
|
|
||
|
|
@return: The adapter instantiated.
|
||
|
|
"""
|
||
|
|
adapt = adapterClass(self)
|
||
|
|
self.addComponent(adapt, ignoreClass)
|
||
|
|
return adapt
|
||
|
|
|
||
|
|
def setComponent(self, interfaceClass, component):
|
||
|
|
"""
|
||
|
|
Cache a provider of the given interface.
|
||
|
|
"""
|
||
|
|
self._adapterCache[reflect.qual(interfaceClass)] = component
|
||
|
|
|
||
|
|
def addComponent(self, component, ignoreClass=0):
|
||
|
|
"""
|
||
|
|
Add a component to me, for all appropriate interfaces.
|
||
|
|
|
||
|
|
In order to determine which interfaces are appropriate, the component's
|
||
|
|
provided interfaces will be scanned.
|
||
|
|
|
||
|
|
If the argument 'ignoreClass' is True, then all interfaces are
|
||
|
|
considered appropriate.
|
||
|
|
|
||
|
|
Otherwise, an 'appropriate' interface is one for which its class has
|
||
|
|
been registered as an adapter for my class according to the rules of
|
||
|
|
getComponent.
|
||
|
|
|
||
|
|
@return: the list of appropriate interfaces
|
||
|
|
"""
|
||
|
|
for iface in declarations.providedBy(component):
|
||
|
|
if (ignoreClass or
|
||
|
|
(self.locateAdapterClass(self.__class__, iface, None)
|
||
|
|
== component.__class__)):
|
||
|
|
self._adapterCache[reflect.qual(iface)] = component
|
||
|
|
|
||
|
|
def unsetComponent(self, interfaceClass):
|
||
|
|
"""Remove my component specified by the given interface class."""
|
||
|
|
del self._adapterCache[reflect.qual(interfaceClass)]
|
||
|
|
|
||
|
|
def removeComponent(self, component):
|
||
|
|
"""
|
||
|
|
Remove the given component from me entirely, for all interfaces for which
|
||
|
|
it has been registered.
|
||
|
|
|
||
|
|
@return: a list of the interfaces that were removed.
|
||
|
|
"""
|
||
|
|
l = []
|
||
|
|
for k, v in list(self._adapterCache.items()):
|
||
|
|
if v is component:
|
||
|
|
del self._adapterCache[k]
|
||
|
|
l.append(reflect.namedObject(k))
|
||
|
|
return l
|
||
|
|
|
||
|
|
def getComponent(self, interface, default=None):
|
||
|
|
"""Create or retrieve an adapter for the given interface.
|
||
|
|
|
||
|
|
If such an adapter has already been created, retrieve it from the cache
|
||
|
|
that this instance keeps of all its adapters. Adapters created through
|
||
|
|
this mechanism may safely store system-specific state.
|
||
|
|
|
||
|
|
If you want to register an adapter that will be created through
|
||
|
|
getComponent, but you don't require (or don't want) your adapter to be
|
||
|
|
cached and kept alive for the lifetime of this Componentized object,
|
||
|
|
set the attribute 'temporaryAdapter' to True on your adapter class.
|
||
|
|
|
||
|
|
If you want to automatically register an adapter for all appropriate
|
||
|
|
interfaces (with addComponent), set the attribute 'multiComponent' to
|
||
|
|
True on your adapter class.
|
||
|
|
"""
|
||
|
|
k = reflect.qual(interface)
|
||
|
|
if k in self._adapterCache:
|
||
|
|
return self._adapterCache[k]
|
||
|
|
else:
|
||
|
|
adapter = interface.__adapt__(self)
|
||
|
|
if adapter is not None and not (
|
||
|
|
hasattr(adapter, "temporaryAdapter") and
|
||
|
|
adapter.temporaryAdapter):
|
||
|
|
self._adapterCache[k] = adapter
|
||
|
|
if (hasattr(adapter, "multiComponent") and
|
||
|
|
adapter.multiComponent):
|
||
|
|
self.addComponent(adapter)
|
||
|
|
if adapter is None:
|
||
|
|
return default
|
||
|
|
return adapter
|
||
|
|
|
||
|
|
|
||
|
|
def __conform__(self, interface):
|
||
|
|
return self.getComponent(interface)
|
||
|
|
|
||
|
|
|
||
|
|
class ReprableComponentized(Componentized):
|
||
|
|
def __init__(self):
|
||
|
|
Componentized.__init__(self)
|
||
|
|
|
||
|
|
def __repr__(self):
|
||
|
|
from pprint import pprint
|
||
|
|
sio = NativeStringIO()
|
||
|
|
pprint(self._adapterCache, sio)
|
||
|
|
return sio.getvalue()
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
def proxyForInterface(iface, originalAttribute='original'):
|
||
|
|
"""
|
||
|
|
Create a class which proxies all method calls which adhere to an interface
|
||
|
|
to another provider of that interface.
|
||
|
|
|
||
|
|
This function is intended for creating specialized proxies. The typical way
|
||
|
|
to use it is by subclassing the result::
|
||
|
|
|
||
|
|
class MySpecializedProxy(proxyForInterface(IFoo)):
|
||
|
|
def someInterfaceMethod(self, arg):
|
||
|
|
if arg == 3:
|
||
|
|
return 3
|
||
|
|
return self.original.someInterfaceMethod(arg)
|
||
|
|
|
||
|
|
@param iface: The Interface to which the resulting object will conform, and
|
||
|
|
which the wrapped object must provide.
|
||
|
|
|
||
|
|
@param originalAttribute: name of the attribute used to save the original
|
||
|
|
object in the resulting class. Default to C{original}.
|
||
|
|
@type originalAttribute: C{str}
|
||
|
|
|
||
|
|
@return: A class whose constructor takes the original object as its only
|
||
|
|
argument. Constructing the class creates the proxy.
|
||
|
|
"""
|
||
|
|
def __init__(self, original):
|
||
|
|
setattr(self, originalAttribute, original)
|
||
|
|
contents = {"__init__": __init__}
|
||
|
|
for name in iface:
|
||
|
|
contents[name] = _ProxyDescriptor(name, originalAttribute)
|
||
|
|
proxy = type("(Proxy for %s)"
|
||
|
|
% (reflect.qual(iface),), (object,), contents)
|
||
|
|
declarations.classImplements(proxy, iface)
|
||
|
|
return proxy
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
class _ProxiedClassMethod(object):
|
||
|
|
"""
|
||
|
|
A proxied class method.
|
||
|
|
|
||
|
|
@ivar methodName: the name of the method which this should invoke when
|
||
|
|
called.
|
||
|
|
@type methodName: C{str}
|
||
|
|
|
||
|
|
@ivar originalAttribute: name of the attribute of the proxy where the
|
||
|
|
original object is stored.
|
||
|
|
@type orginalAttribute: C{str}
|
||
|
|
"""
|
||
|
|
def __init__(self, methodName, originalAttribute):
|
||
|
|
self.methodName = methodName
|
||
|
|
self.originalAttribute = originalAttribute
|
||
|
|
|
||
|
|
|
||
|
|
def __call__(self, oself, *args, **kw):
|
||
|
|
"""
|
||
|
|
Invoke the specified L{methodName} method of the C{original} attribute
|
||
|
|
for proxyForInterface.
|
||
|
|
|
||
|
|
@param oself: an instance of a L{proxyForInterface} object.
|
||
|
|
|
||
|
|
@return: the result of the underlying method.
|
||
|
|
"""
|
||
|
|
original = getattr(oself, self.originalAttribute)
|
||
|
|
actualMethod = getattr(original, self.methodName)
|
||
|
|
return actualMethod(*args, **kw)
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
class _ProxyDescriptor(object):
|
||
|
|
"""
|
||
|
|
A descriptor which will proxy attribute access, mutation, and
|
||
|
|
deletion to the L{original} attribute of the object it is being accessed
|
||
|
|
from.
|
||
|
|
|
||
|
|
@ivar attributeName: the name of the attribute which this descriptor will
|
||
|
|
retrieve from instances' C{original} attribute.
|
||
|
|
@type attributeName: C{str}
|
||
|
|
|
||
|
|
@ivar originalAttribute: name of the attribute of the proxy where the
|
||
|
|
original object is stored.
|
||
|
|
@type orginalAttribute: C{str}
|
||
|
|
"""
|
||
|
|
def __init__(self, attributeName, originalAttribute):
|
||
|
|
self.attributeName = attributeName
|
||
|
|
self.originalAttribute = originalAttribute
|
||
|
|
|
||
|
|
|
||
|
|
def __get__(self, oself, type=None):
|
||
|
|
"""
|
||
|
|
Retrieve the C{self.attributeName} property from L{oself}.
|
||
|
|
"""
|
||
|
|
if oself is None:
|
||
|
|
return _ProxiedClassMethod(self.attributeName,
|
||
|
|
self.originalAttribute)
|
||
|
|
original = getattr(oself, self.originalAttribute)
|
||
|
|
return getattr(original, self.attributeName)
|
||
|
|
|
||
|
|
|
||
|
|
def __set__(self, oself, value):
|
||
|
|
"""
|
||
|
|
Set the C{self.attributeName} property of L{oself}.
|
||
|
|
"""
|
||
|
|
original = getattr(oself, self.originalAttribute)
|
||
|
|
setattr(original, self.attributeName, value)
|
||
|
|
|
||
|
|
|
||
|
|
def __delete__(self, oself):
|
||
|
|
"""
|
||
|
|
Delete the C{self.attributeName} property of L{oself}.
|
||
|
|
"""
|
||
|
|
original = getattr(oself, self.originalAttribute)
|
||
|
|
delattr(original, self.attributeName)
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
__all__ = [
|
||
|
|
"registerAdapter", "getAdapterFactory",
|
||
|
|
"Adapter", "Componentized", "ReprableComponentized", "getRegistry",
|
||
|
|
"proxyForInterface",
|
||
|
|
]
|