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authorGeorg Brandl <georg@python.org>2010-12-30 21:33:07 (GMT)
committerGeorg Brandl <georg@python.org>2010-12-30 21:33:07 (GMT)
commit7fafbc95c0c963438197c9a43fe893c4ea6fe759 (patch)
tree5c9ceda4bdc5260236a230554b9ed56b8c0cdbd3 /Demo/newmetaclasses/Eiffel.py
parent6f17e2df29a865a29447531e89fb22be710e382d (diff)
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More cleanup: Move some demos into a dedicated Tools/demo dir, move 2to3 demo to Tools, and remove all the other Demo content.
Diffstat (limited to 'Demo/newmetaclasses/Eiffel.py')
-rw-r--r--Demo/newmetaclasses/Eiffel.py141
1 files changed, 0 insertions, 141 deletions
diff --git a/Demo/newmetaclasses/Eiffel.py b/Demo/newmetaclasses/Eiffel.py
deleted file mode 100644
index 15fa58a..0000000
--- a/Demo/newmetaclasses/Eiffel.py
+++ /dev/null
@@ -1,141 +0,0 @@
-"""Support Eiffel-style preconditions and postconditions."""
-
-from types import FunctionType as function
-
-class EiffelBaseMetaClass(type):
-
- def __new__(meta, name, bases, dict):
- meta.convert_methods(dict)
- return super(EiffelBaseMetaClass, meta).__new__(meta, name, bases,
- dict)
-
- @classmethod
- def convert_methods(cls, dict):
- """Replace functions in dict with EiffelMethod wrappers.
-
- The dict is modified in place.
-
- If a method ends in _pre or _post, it is removed from the dict
- regardless of whether there is a corresponding method.
- """
- # find methods with pre or post conditions
- methods = []
- for k, v in dict.items():
- if k.endswith('_pre') or k.endswith('_post'):
- assert isinstance(v, function)
- elif isinstance(v, function):
- methods.append(k)
- for m in methods:
- pre = dict.get("%s_pre" % m)
- post = dict.get("%s_post" % m)
- if pre or post:
- dict[k] = cls.make_eiffel_method(dict[m], pre, post)
-
-class EiffelMetaClass1(EiffelBaseMetaClass):
- # an implementation of the "eiffel" meta class that uses nested functions
-
- @staticmethod
- def make_eiffel_method(func, pre, post):
- def method(self, *args, **kwargs):
- if pre:
- pre(self, *args, **kwargs)
- x = func(self, *args, **kwargs)
- if post:
- post(self, x, *args, **kwargs)
- return x
-
- if func.__doc__:
- method.__doc__ = func.__doc__
-
- return method
-
-class EiffelMethodWrapper:
-
- def __init__(self, inst, descr):
- self._inst = inst
- self._descr = descr
-
- def __call__(self, *args, **kwargs):
- return self._descr.callmethod(self._inst, args, kwargs)
-
-class EiffelDescriptor(object):
-
- def __init__(self, func, pre, post):
- self._func = func
- self._pre = pre
- self._post = post
-
- self.__name__ = func.__name__
- self.__doc__ = func.__doc__
-
- def __get__(self, obj, cls):
- return EiffelMethodWrapper(obj, self)
-
- def callmethod(self, inst, args, kwargs):
- if self._pre:
- self._pre(inst, *args, **kwargs)
- x = self._func(inst, *args, **kwargs)
- if self._post:
- self._post(inst, x, *args, **kwargs)
- return x
-
-class EiffelMetaClass2(EiffelBaseMetaClass):
- # an implementation of the "eiffel" meta class that uses descriptors
-
- make_eiffel_method = EiffelDescriptor
-
-def _test(metaclass):
- class Eiffel(metaclass=metaclass):
- pass
-
- class Test(Eiffel):
-
- def m(self, arg):
- """Make it a little larger"""
- return arg + 1
-
- def m2(self, arg):
- """Make it a little larger"""
- return arg + 1
-
- def m2_pre(self, arg):
- assert arg > 0
-
- def m2_post(self, result, arg):
- assert result > arg
-
- class Sub(Test):
- def m2(self, arg):
- return arg**2
- def m2_post(self, Result, arg):
- super(Sub, self).m2_post(Result, arg)
- assert Result < 100
-
- t = Test()
- t.m(1)
- t.m2(1)
- try:
- t.m2(0)
- except AssertionError:
- pass
- else:
- assert False
-
- s = Sub()
- try:
- s.m2(1)
- except AssertionError:
- pass # result == arg
- else:
- assert False
- try:
- s.m2(10)
- except AssertionError:
- pass # result == 100
- else:
- assert False
- s.m2(5)
-
-if __name__ == "__main__":
- _test(EiffelMetaClass1)
- _test(EiffelMetaClass2)