def validate(obj, classes=None):
"""
Validate the object against the classes.
This is like isinstance, except that it validates that the object
has implemented all the abstract methods/properties of all the
classes.
"""
if classes is None:
classes = obj.mro()
#classes.extend(obj.__implements__)
if not isinstance(classes, (list, tuple)):
classes = (classes,)
abstracts = set()
for cls in classes:
if not isinstance(cls, type):
raise TypeError("Can only validate against classes")
for name in getattr(cls, "__abstractmethods__", set()):
value = getattr(obj, name, None)
if not value:
abstracts.add(name)
elif getattr(value, "__isabstractmethod__", False):
abstracts.add(name)
if abstracts:
sorted_methods = sorted(abstracts)
joined = ", ".join(sorted_methods)
try:
name = obj.__name__
except AttributeError:
name = obj
msg = "{} does not implement abstract methods {}"
raise TypeError(msg.format(name, joined))
def conforms(classes):
"""A class decorator factory for validating against an ABC."""
def decorator(cls):
if not __debug__:
return cls
if not isinstance(cls, type):
raise TypeError("Can only validate classes")
validate(cls, classes)
return cls
return decorator
Diff to Previous Revision
--- revision 3 2011-05-21 19:05:53
+++ revision 4 2011-05-21 19:14:19
@@ -43,25 +43,3 @@
validate(cls, classes)
return cls
return decorator
-
-
-# Example:
-
-from abc import abstractmethod, abstractproperty, ABCMeta
-
-class X(metaclass=ABCMeta):
- @abstractproperty
- def name(self): pass
- @abstractmethod
- def f(self): pass
-
-@X.register(C)
-class C:
- def __init__(self, name):
- self.name = name
- def f(self): pass
-
-obj = C("some name")
-validate(obj, X)
-
-# this works
