Viewing file:  interface.py (22.48 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
##############################################################################
#
# Copyright (c) 2001-2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Interface object implementation
$Id: interface.py 105433 2009-11-02 08:33:25Z ctheune $
"""
from __future__ import generators
import sys
import warnings
import weakref
from types import FunctionType
from ro import ro
from zope.interface.exceptions import Invalid
CO_VARARGS = 4
CO_VARKEYWORDS = 8
TAGGED_DATA = '__interface_tagged_values__'
_decorator_non_return = object()
def invariant(call):
f_locals = sys._getframe(1).f_locals
tags = f_locals.setdefault(TAGGED_DATA, {})
invariants = tags.setdefault('invariants', [])
invariants.append(call)
return _decorator_non_return
def taggedValue(key, value):
"""Attaches a tagged value to an interface at definition time."""
f_locals = sys._getframe(1).f_locals
tagged_values = f_locals.setdefault(TAGGED_DATA, {})
tagged_values[key] = value
return _decorator_non_return
class Element(object):
# We can't say this yet because we don't have enough
# infrastructure in place.
#
#implements(IElement)
def __init__(self, __name__, __doc__=''):
"""Create an 'attribute' description
"""
if not __doc__ and __name__.find(' ') >= 0:
__doc__ = __name__
__name__ = None
self.__name__=__name__
self.__doc__=__doc__
self.__tagged_values = {}
def getName(self):
""" Returns the name of the object. """
return self.__name__
def getDoc(self):
""" Returns the documentation for the object. """
return self.__doc__
def getTaggedValue(self, tag):
""" Returns the value associated with 'tag'. """
return self.__tagged_values[tag]
def queryTaggedValue(self, tag, default=None):
""" Returns the value associated with 'tag'. """
return self.__tagged_values.get(tag, default)
def getTaggedValueTags(self):
""" Returns a list of all tags. """
return self.__tagged_values.keys()
def setTaggedValue(self, tag, value):
""" Associates 'value' with 'key'. """
self.__tagged_values[tag] = value
class SpecificationBasePy(object):
def providedBy(self, ob):
"""Is the interface implemented by an object
>>> from zope.interface import *
>>> class I1(Interface):
... pass
>>> class C(object):
... implements(I1)
>>> c = C()
>>> class X(object):
... pass
>>> x = X()
>>> I1.providedBy(x)
False
>>> I1.providedBy(C)
False
>>> I1.providedBy(c)
True
>>> directlyProvides(x, I1)
>>> I1.providedBy(x)
True
>>> directlyProvides(C, I1)
>>> I1.providedBy(C)
True
"""
spec = providedBy(ob)
return self in spec._implied
def implementedBy(self, cls):
"""Test whether the specification is implemented by a class or factory.
Raise TypeError if argument is neither a class nor a callable."""
spec = implementedBy(cls)
return self in spec._implied
def isOrExtends(self, interface):
"""Is the interface the same as or extend the given interface
Examples::
>>> from zope.interface import Interface
>>> from zope.interface.declarations import Declaration
>>> class I1(Interface): pass
...
>>> class I2(I1): pass
...
>>> class I3(Interface): pass
...
>>> class I4(I3): pass
...
>>> spec = Declaration()
>>> int(spec.extends(Interface))
1
>>> spec = Declaration(I2)
>>> int(spec.extends(Interface))
1
>>> int(spec.extends(I1))
1
>>> int(spec.extends(I2))
1
>>> int(spec.extends(I3))
0
>>> int(spec.extends(I4))
0
"""
return interface in self._implied
__call__ = isOrExtends
SpecificationBase = SpecificationBasePy
_marker = object()
class InterfaceBasePy(object):
"""Base class that wants to be replaced with a C base :)
"""
def __call__(self, obj, alternate=_marker):
"""Adapt an object to the interface
"""
conform = getattr(obj, '__conform__', None)
if conform is not None:
adapter = self._call_conform(conform)
if adapter is not None:
return adapter
adapter = self.__adapt__(obj)
if adapter is not None:
return adapter
elif alternate is not _marker:
return alternate
else:
raise TypeError("Could not adapt", obj, self)
def __adapt__(self, obj):
"""Adapt an object to the reciever
"""
if self.providedBy(obj):
return obj
for hook in adapter_hooks:
adapter = hook(self, obj)
if adapter is not None:
return adapter
InterfaceBase = InterfaceBasePy
adapter_hooks = []
try:
import _zope_interface_coptimizations
except ImportError:
pass
else:
from _zope_interface_coptimizations import SpecificationBase
from _zope_interface_coptimizations import InterfaceBase, adapter_hooks
class Specification(SpecificationBase):
"""Specifications
An interface specification is used to track interface declarations
and component registrations.
This class is a base class for both interfaces themselves and for
interface specifications (declarations).
Specifications are mutable. If you reassign their cases, their
relations with other specifications are adjusted accordingly.
For example:
>>> from zope.interface import Interface
>>> class I1(Interface):
... pass
>>> class I2(I1):
... pass
>>> class I3(I2):
... pass
>>> [i.__name__ for i in I1.__bases__]
['Interface']
>>> [i.__name__ for i in I2.__bases__]
['I1']
>>> I3.extends(I1)
1
>>> I2.__bases__ = (Interface, )
>>> [i.__name__ for i in I2.__bases__]
['Interface']
>>> I3.extends(I1)
0
"""
# Copy some base class methods for speed
isOrExtends = SpecificationBase.isOrExtends
providedBy = SpecificationBase.providedBy
def __init__(self, bases=()):
self._implied = {}
self.dependents = weakref.WeakKeyDictionary()
self.__bases__ = tuple(bases)
def subscribe(self, dependent):
self.dependents[dependent] = self.dependents.get(dependent, 0) + 1
def unsubscribe(self, dependent):
n = self.dependents.get(dependent, 0) - 1
if not n:
del self.dependents[dependent]
elif n > 0:
self.dependents[dependent] = n
else:
raise KeyError(dependent)
def __setBases(self, bases):
# Register ourselves as a dependent of our old bases
for b in self.__bases__:
b.unsubscribe(self)
# Register ourselves as a dependent of our bases
self.__dict__['__bases__'] = bases
for b in bases:
b.subscribe(self)
self.changed(self)
__bases__ = property(
lambda self: self.__dict__.get('__bases__', ()),
__setBases,
)
def changed(self, originally_changed):
"""We, or something we depend on, have changed
"""
implied = self._implied
implied.clear()
ancestors = ro(self)
try:
if Interface not in ancestors:
ancestors.append(Interface)
except NameError:
pass # defining Interface itself
self.__sro__ = tuple(ancestors)
self.__iro__ = tuple([ancestor for ancestor in ancestors
if isinstance(ancestor, InterfaceClass)
])
for ancestor in ancestors:
# We directly imply our ancestors:
implied[ancestor] = ()
# Now, advise our dependents of change:
for dependent in self.dependents.keys():
dependent.changed(originally_changed)
def interfaces(self):
"""Return an iterator for the interfaces in the specification
for example::
>>> from zope.interface import Interface
>>> class I1(Interface): pass
...
>>> class I2(I1): pass
...
>>> class I3(Interface): pass
...
>>> class I4(I3): pass
...
>>> spec = Specification((I2, I3))
>>> spec = Specification((I4, spec))
>>> i = spec.interfaces()
>>> i.next().getName()
'I4'
>>> i.next().getName()
'I2'
>>> i.next().getName()
'I3'
>>> list(i)
[]
"""
seen = {}
for base in self.__bases__:
for interface in base.interfaces():
if interface not in seen:
seen[interface] = 1
yield interface
def extends(self, interface, strict=True):
"""Does the specification extend the given interface?
Test whether an interface in the specification extends the
given interface
Examples::
>>> from zope.interface import Interface
>>> from zope.interface.declarations import Declaration
>>> class I1(Interface): pass
...
>>> class I2(I1): pass
...
>>> class I3(Interface): pass
...
>>> class I4(I3): pass
...
>>> spec = Declaration()
>>> int(spec.extends(Interface))
1
>>> spec = Declaration(I2)
>>> int(spec.extends(Interface))
1
>>> int(spec.extends(I1))
1
>>> int(spec.extends(I2))
1
>>> int(spec.extends(I3))
0
>>> int(spec.extends(I4))
0
>>> I2.extends(I2)
0
>>> I2.extends(I2, False)
1
>>> I2.extends(I2, strict=False)
1
"""
return ((interface in self._implied)
and
((not strict) or (self != interface))
)
def weakref(self, callback=None):
return weakref.ref(self, callback)
def get(self, name, default=None):
"""Query for an attribute description
"""
try:
attrs = self._v_attrs
except AttributeError:
attrs = self._v_attrs = {}
attr = attrs.get(name)
if attr is None:
for iface in self.__iro__:
attr = iface.direct(name)
if attr is not None:
attrs[name] = attr
break
if attr is None:
return default
else:
return attr
class InterfaceClass(Element, InterfaceBase, Specification):
"""Prototype (scarecrow) Interfaces Implementation."""
# We can't say this yet because we don't have enough
# infrastructure in place.
#
#implements(IInterface)
def __init__(self, name, bases=(), attrs=None, __doc__=None,
__module__=None):
if attrs is None:
attrs = {}
if __module__ is None:
__module__ = attrs.get('__module__')
if isinstance(__module__, str):
del attrs['__module__']
else:
try:
# Figure out what module defined the interface.
# This is how cPython figures out the module of
# a class, but of course it does it in C. :-/
__module__ = sys._getframe(1).f_globals['__name__']
except (AttributeError, KeyError):
pass
self.__module__ = __module__
d = attrs.get('__doc__')
if d is not None:
if not isinstance(d, Attribute):
if __doc__ is None:
__doc__ = d
del attrs['__doc__']
if __doc__ is None:
__doc__ = ''
Element.__init__(self, name, __doc__)
tagged_data = attrs.pop(TAGGED_DATA, None)
if tagged_data is not None:
for key, val in tagged_data.items():
self.setTaggedValue(key, val)
for base in bases:
if not isinstance(base, InterfaceClass):
raise TypeError('Expected base interfaces')
Specification.__init__(self, bases)
# Make sure that all recorded attributes (and methods) are of type
# `Attribute` and `Method`
for name, attr in attrs.items():
if isinstance(attr, Attribute):
attr.interface = self
if not attr.__name__:
attr.__name__ = name
elif isinstance(attr, FunctionType):
attrs[name] = fromFunction(attr, self, name=name)
elif attr is _decorator_non_return:
del attrs[name]
else:
raise InvalidInterface("Concrete attribute, " + name)
self.__attrs = attrs
self.__identifier__ = "%s.%s" % (self.__module__, self.__name__)
def interfaces(self):
"""Return an iterator for the interfaces in the specification
for example::
>>> from zope.interface import Interface
>>> class I1(Interface): pass
...
>>>
>>> i = I1.interfaces()
>>> i.next().getName()
'I1'
>>> list(i)
[]
"""
yield self
def getBases(self):
return self.__bases__
def isEqualOrExtendedBy(self, other):
"""Same interface or extends?"""
return self == other or other.extends(self)
def names(self, all=False):
"""Return the attribute names defined by the interface."""
if not all:
return self.__attrs.keys()
r = self.__attrs.copy()
for base in self.__bases__:
r.update(dict.fromkeys(base.names(all)))
return r.keys()
def __iter__(self):
return iter(self.names(all=True))
def namesAndDescriptions(self, all=False):
"""Return attribute names and descriptions defined by interface."""
if not all:
return self.__attrs.items()
r = {}
for base in self.__bases__[::-1]:
r.update(dict(base.namesAndDescriptions(all)))
r.update(self.__attrs)
return r.items()
def getDescriptionFor(self, name):
"""Return the attribute description for the given name."""
r = self.get(name)
if r is not None:
return r
raise KeyError(name)
__getitem__ = getDescriptionFor
def __contains__(self, name):
return self.get(name) is not None
def direct(self, name):
return self.__attrs.get(name)
def queryDescriptionFor(self, name, default=None):
return self.get(name, default)
def deferred(self):
"""Return a defered class corresponding to the interface."""
if hasattr(self, "_deferred"): return self._deferred
klass={}
exec "class %s: pass" % self.__name__ in klass
klass=klass[self.__name__]
self.__d(klass.__dict__)
self._deferred=klass
return klass
def validateInvariants(self, obj, errors=None):
"""validate object to defined invariants."""
for call in self.queryTaggedValue('invariants', []):
try:
call(obj)
except Invalid, e:
if errors is None:
raise
else:
errors.append(e)
for base in self.__bases__:
try:
base.validateInvariants(obj, errors)
except Invalid:
if errors is None:
raise
if errors:
raise Invalid(errors)
def _getInterface(self, ob, name):
"""Retrieve a named interface."""
return None
def __d(self, dict):
for k, v in self.__attrs.items():
if isinstance(v, Method) and not (k in dict):
dict[k]=v
for b in self.__bases__:
b.__d(dict)
def __repr__(self):
try:
return self._v_repr
except AttributeError:
name = self.__name__
m = self.__module__
if m:
name = '%s.%s' % (m, name)
r = "<%s %s>" % (self.__class__.__name__, name)
self._v_repr = r
return r
def _call_conform(self, conform):
try:
return conform(self)
except TypeError:
# We got a TypeError. It might be an error raised by
# the __conform__ implementation, or *we* may have
# made the TypeError by calling an unbound method
# (object is a class). In the later case, we behave
# as though there is no __conform__ method. We can
# detect this case by checking whether there is more
# than one traceback object in the traceback chain:
if sys.exc_info()[2].tb_next is not None:
# There is more than one entry in the chain, so
# reraise the error:
raise
# This clever trick is from Phillip Eby
return None
def __reduce__(self):
return self.__name__
def __cmp(self, o1, o2):
# Yes, I did mean to name this __cmp, rather than __cmp__.
# It is a private method used by __lt__ and __gt__.
# I don't want to override __eq__ because I want the default
# __eq__, which is really fast.
"""Make interfaces sortable
TODO: It would ne nice if:
More specific interfaces should sort before less specific ones.
Otherwise, sort on name and module.
But this is too complicated, and we're going to punt on it
for now.
For now, sort on interface and module name.
None is treated as a pseudo interface that implies the loosest
contact possible, no contract. For that reason, all interfaces
sort before None.
"""
if o1 == o2:
return 0
if o1 is None:
return 1
if o2 is None:
return -1
n1 = (getattr(o1, '__name__', ''),
getattr(getattr(o1, '__module__', None), '__name__', ''))
n2 = (getattr(o2, '__name__', ''),
getattr(getattr(o2, '__module__', None), '__name__', ''))
return cmp(n1, n2)
def __lt__(self, other):
c = self.__cmp(self, other)
#print '<', self, other, c < 0, c
return c < 0
def __gt__(self, other):
c = self.__cmp(self, other)
#print '>', self, other, c > 0, c
return c > 0
Interface = InterfaceClass("Interface", __module__ = 'zope.interface')
class Attribute(Element):
"""Attribute descriptions
"""
# We can't say this yet because we don't have enough
# infrastructure in place.
#
# implements(IAttribute)
interface = None
class Method(Attribute):
"""Method interfaces
The idea here is that you have objects that describe methods.
This provides an opportunity for rich meta-data.
"""
# We can't say this yet because we don't have enough
# infrastructure in place.
#
# implements(IMethod)
def __call__(self, *args, **kw):
raise BrokenImplementation(self.interface, self.__name__)
def getSignatureInfo(self):
return {'positional': self.positional,
'required': self.required,
'optional': self.optional,
'varargs': self.varargs,
'kwargs': self.kwargs,
}
def getSignatureString(self):
sig = []
for v in self.positional:
sig.append(v)
if v in self.optional.keys():
sig[-1] += "=" + `self.optional[v]`
if self.varargs:
sig.append("*" + self.varargs)
if self.kwargs:
sig.append("**" + self.kwargs)
return "(%s)" % ", ".join(sig)
def fromFunction(func, interface=None, imlevel=0, name=None):
name = name or func.__name__
method = Method(name, func.__doc__)
defaults = func.func_defaults or ()
code = func.func_code
# Number of positional arguments
na = code.co_argcount-imlevel
names = code.co_varnames[imlevel:]
opt = {}
# Number of required arguments
nr = na-len(defaults)
if nr < 0:
defaults=defaults[-nr:]
nr = 0
# Determine the optional arguments.
opt.update(dict(zip(names[nr:], defaults)))
method.positional = names[:na]
method.required = names[:nr]
method.optional = opt
argno = na
# Determine the function's variable argument's name (i.e. *args)
if code.co_flags & CO_VARARGS:
method.varargs = names[argno]
argno = argno + 1
else:
method.varargs = None
# Determine the function's keyword argument's name (i.e. **kw)
if code.co_flags & CO_VARKEYWORDS:
method.kwargs = names[argno]
else:
method.kwargs = None
method.interface = interface
for key, value in func.__dict__.items():
method.setTaggedValue(key, value)
return method
def fromMethod(meth, interface=None, name=None):
func = meth.im_func
return fromFunction(func, interface, imlevel=1, name=name)
# Now we can create the interesting interfaces and wire them up:
def _wire():
from zope.interface.declarations import classImplements
from zope.interface.interfaces import IAttribute
classImplements(Attribute, IAttribute)
from zope.interface.interfaces import IMethod
classImplements(Method, IMethod)
from zope.interface.interfaces import IInterface, ISpecification
classImplements(InterfaceClass, IInterface)
classImplements(Specification, ISpecification)
# We import this here to deal with module dependencies.
from zope.interface.declarations import providedBy, implementedBy
from zope.interface.exceptions import InvalidInterface
from zope.interface.exceptions import BrokenImplementation
|