/usr/lib/python2.7/dist-packages/protocols/interfaces.py is in python-protocols 1.0a.svn20070625-7.
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from __future__ import generators
__all__ = [
'Protocol', 'InterfaceClass', 'Interface',
'AbstractBase', 'AbstractBaseMeta',
'IAdapterFactory', 'IProtocol',
'IAdaptingProtocol', 'IOpenProtocol', 'IOpenProvider',
'IOpenImplementor', 'IImplicationListener', 'Attribute', 'Variation'
]
import api
from advice import metamethod, classicMRO, mkRef
from adapters import composeAdapters, updateWithSimplestAdapter
from adapters import NO_ADAPTER_NEEDED, DOES_NOT_SUPPORT
from types import InstanceType
# Thread locking support
try:
from thread import allocate_lock
except ImportError:
try:
from dummy_thread import allocate_lock
except ImportError:
class allocate_lock(object):
__slots__ = ()
def acquire(*args): pass
def release(*args): pass
# Trivial interface implementation
class Protocol:
"""Generic protocol w/type-based adapter registry"""
def __init__(self):
self.__adapters = {}
self.__implies = {}
self.__listeners = None
self.__lock = allocate_lock()
def getImpliedProtocols(self):
# This is messy so it can clean out weakrefs, but this method is only
# called for declaration activities and is thus not at all
# speed-critical. It's more important that we support weak refs to
# implied protocols, so that dynamically created subset protocols can
# be garbage collected.
out = []
add = out.append
self.__lock.acquire() # we might clean out dead weakrefs
try:
for k,v in self.__implies.items():
proto = k()
if proto is None:
del self.__implies[k]
else:
add((proto,v))
return out
finally:
self.__lock.release()
def addImpliedProtocol(self,proto,adapter=NO_ADAPTER_NEEDED,depth=1):
self.__lock.acquire()
try:
key = mkRef(proto)
if not updateWithSimplestAdapter(
self.__implies, key, adapter, depth
):
return self.__implies[key][0]
finally:
self.__lock.release()
# Always register implied protocol with classes, because they should
# know if we break the implication link between two protocols
for klass,(baseAdapter,d) in self.__adapters.items():
api.declareAdapterForType(
proto,composeAdapters(baseAdapter,self,adapter),klass,depth+d
)
if self.__listeners:
for listener in self.__listeners.keys(): # Must use keys()!
listener.newProtocolImplied(self, proto, adapter, depth)
return adapter
addImpliedProtocol = metamethod(addImpliedProtocol)
def registerImplementation(self,klass,adapter=NO_ADAPTER_NEEDED,depth=1):
self.__lock.acquire()
try:
if not updateWithSimplestAdapter(
self.__adapters,klass,adapter,depth
):
return self.__adapters[klass][0]
finally:
self.__lock.release()
if adapter is DOES_NOT_SUPPORT:
# Don't register non-support with implied protocols, because
# "X implies Y" and "not X" doesn't imply "not Y". In effect,
# explicitly registering DOES_NOT_SUPPORT for a type is just a
# way to "disinherit" a superclass' claim to support something.
return adapter
for proto, (extender,d) in self.getImpliedProtocols():
api.declareAdapterForType(
proto, composeAdapters(adapter,self,extender), klass, depth+d
)
return adapter
registerImplementation = metamethod(registerImplementation)
def registerObject(self, ob, adapter=NO_ADAPTER_NEEDED,depth=1):
# Object needs to be able to handle registration
if api.adapt(ob,IOpenProvider).declareProvides(self,adapter,depth):
if adapter is DOES_NOT_SUPPORT:
return # non-support doesn't imply non-support of implied
# Handle implied protocols
for proto, (extender,d) in self.getImpliedProtocols():
api.declareAdapterForObject(
proto, composeAdapters(adapter,self,extender), ob, depth+d
)
registerObject = metamethod(registerObject)
def __adapt__(self, obj):
get = self.__adapters.get
try:
typ = obj.__class__
except AttributeError:
typ = type(obj)
try:
mro = typ.__mro__
except AttributeError:
# Note: this adds 'InstanceType' and 'object' to end of MRO
mro = classicMRO(typ,extendedClassic=True)
for klass in mro:
factory=get(klass)
if factory is not None:
return factory[0](obj)
try:
from _speedups import Protocol__adapt__ as __adapt__
except ImportError:
pass
__adapt__ = metamethod(__adapt__)
def addImplicationListener(self, listener):
self.__lock.acquire()
try:
if self.__listeners is None:
from weakref import WeakKeyDictionary
self.__listeners = WeakKeyDictionary()
self.__listeners[listener] = 1
finally:
self.__lock.release()
addImplicationListener = metamethod(addImplicationListener)
def __call__(self, ob, default=api._marker):
"""Adapt to this protocol"""
return api.adapt(ob,self,default)
# Use faster __call__ method, if possible
# XXX it could be even faster if the __call__ were in the tp_call slot
# XXX directly, but Pyrex doesn't have a way to do that AFAIK.
try:
from _speedups import Protocol__call__
except ImportError:
pass
else:
from new import instancemethod
Protocol.__call__ = instancemethod(Protocol__call__, None, Protocol)
class AbstractBaseMeta(Protocol, type):
"""Metaclass for 'AbstractBase' - a protocol that's also a class
(Note that this should not be used as an explicit metaclass - always
subclass from 'AbstractBase' or 'Interface' instead.)
"""
def __init__(self, __name__, __bases__, __dict__):
type.__init__(self, __name__, __bases__, __dict__)
Protocol.__init__(self)
for b in __bases__:
if isinstance(b,AbstractBaseMeta) and b.__bases__<>(object,):
self.addImpliedProtocol(b)
def __setattr__(self,attr,val):
# We could probably support changing __bases__, as long as we checked
# that no bases are *removed*. But it'd be a pain, since we'd
# have to do callbacks, remove entries from our __implies registry,
# etc. So just punt for now.
if attr=='__bases__':
raise TypeError(
"Can't change interface __bases__", self
)
type.__setattr__(self,attr,val)
__call__ = type.__call__
class AbstractBase(object):
"""Base class for a protocol that's a class"""
__metaclass__ = AbstractBaseMeta
class InterfaceClass(AbstractBaseMeta):
"""Metaclass for 'Interface' - a non-instantiable protocol
(Note that this should not be used as an explicit metaclass - always
subclass from 'AbstractBase' or 'Interface' instead.)
"""
def __call__(self, *__args, **__kw):
if self.__init__ is Interface.__init__:
return Protocol.__call__(self,*__args, **__kw)
else:
return type.__call__(self,*__args, **__kw)
def getBases(self):
return [
b for b in self.__bases__
if isinstance(b,AbstractBaseMeta) and b.__bases__<>(object,)
]
class Interface(object):
__metaclass__ = InterfaceClass
class Variation(Protocol):
"""A variation of a base protocol - "inherits" the base's adapters
See the 'LocalProtocol' example in the reference manual for more info.
"""
def __init__(self, baseProtocol, context = None):
self.baseProtocol = baseProtocol
self.context = context
# Note: Protocol is a ``classic'' class, so we don't use super()
Protocol.__init__(self)
api.declareAdapterForProtocol(self,NO_ADAPTER_NEEDED,baseProtocol)
def __repr__(self):
if self.context is None:
return "Variation(%r)" % self.baseProtocol
return "Variation(%r,%r)" % (self.baseProtocol, self.context)
# Semi-backward compatible 'interface.Attribute'
class Attribute(object):
"""Attribute declaration; should we get rid of this?"""
def __init__(self,doc,name=None,value=None):
self.__doc__ = doc
self.name = name
self.value = value
def __get__(self,ob,typ=None):
if ob is None:
return self
if not self.name:
raise NotImplementedError("Abstract attribute")
try:
return ob.__dict__[self.name]
except KeyError:
return self.value
def __set__(self,ob,val):
if not self.name:
raise NotImplementedError("Abstract attribute")
ob.__dict__[self.name] = val
def __delete__(self,ob):
if not self.name:
raise NotImplementedError("Abstract attribute")
del ob.__dict__[self.name]
def __repr__(self):
return "Attribute: %s" % self.__doc__
# Interfaces and adapters for declaring protocol/type/object relationships
class IAdapterFactory(Interface):
"""Callable that can adapt an object to a protocol"""
def __call__(ob):
"""Return an implementation of protocol for 'ob'"""
class IProtocol(Interface):
"""Object usable as a protocol by 'adapt()'"""
def __hash__():
"""Protocols must be usable as dictionary keys"""
def __eq__(other):
"""Protocols must be comparable with == and !="""
def __ne__(other):
"""Protocols must be comparable with == and !="""
class IAdaptingProtocol(IProtocol):
"""A protocol that potentially knows how to adapt some object to itself"""
def __adapt__(ob):
"""Return 'ob' adapted to protocol, or 'None'"""
class IConformingObject(Interface):
"""An object that potentially knows how to adapt to a protocol"""
def __conform__(protocol):
"""Return an implementation of 'protocol' for self, or 'None'"""
class IOpenProvider(Interface):
"""An object that can be told how to adapt to protocols"""
def declareProvides(protocol, adapter=NO_ADAPTER_NEEDED, depth=1):
"""Register 'adapter' as providing 'protocol' for this object
Return a true value if the provided adapter is the "shortest path" to
'protocol' for the object, or false if a shorter path already existed.
"""
class IOpenImplementor(Interface):
"""Object/type that can be told how its instances adapt to protocols"""
def declareClassImplements(protocol, adapter=NO_ADAPTER_NEEDED, depth=1):
"""Register 'adapter' as implementing 'protocol' for instances"""
class IOpenProtocol(IAdaptingProtocol):
"""A protocol that be told what it implies, and what supports it
Note that these methods are for the use of the declaration APIs only,
and you should NEVER call them directly."""
def addImpliedProtocol(proto, adapter=NO_ADAPTER_NEEDED, depth=1):
"""'adapter' provides conversion from this protocol to 'proto'"""
def registerImplementation(klass, adapter=NO_ADAPTER_NEEDED, depth=1):
"""'adapter' provides protocol for instances of klass"""
def registerObject(ob, adapter=NO_ADAPTER_NEEDED, depth=1):
"""'adapter' provides protocol for 'ob' directly"""
def addImplicationListener(listener):
"""Notify 'listener' whenever protocol has new implied protocol"""
class IImplicationListener(Interface):
def newProtocolImplied(srcProto, destProto, adapter, depth):
"""'srcProto' now implies 'destProto' via 'adapter' at 'depth'"""
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