Python code coverage for Tools/demo/eiffel.py

#	count	content
1	n/a	#!/usr/bin/env python3
2	n/a
3	n/a	"""
4	n/a	Support Eiffel-style preconditions and postconditions for functions.
5	n/a
6	n/a	An example for Python metaclasses.
7	n/a	"""
8	n/a
9	n/a	import unittest
10	n/a	from types import FunctionType as function
11	n/a
12	n/a	class EiffelBaseMetaClass(type):
13	n/a
14	n/a	def __new__(meta, name, bases, dict):
15	n/a	meta.convert_methods(dict)
16	n/a	return super(EiffelBaseMetaClass, meta).__new__(
17	n/a	meta, name, bases, dict)
18	n/a
19	n/a	@classmethod
20	n/a	def convert_methods(cls, dict):
21	n/a	"""Replace functions in dict with EiffelMethod wrappers.
22	n/a
23	n/a	The dict is modified in place.
24	n/a
25	n/a	If a method ends in _pre or _post, it is removed from the dict
26	n/a	regardless of whether there is a corresponding method.
27	n/a	"""
28	n/a	# find methods with pre or post conditions
29	n/a	methods = []
30	n/a	for k, v in dict.items():
31	n/a	if k.endswith('_pre') or k.endswith('_post'):
32	n/a	assert isinstance(v, function)
33	n/a	elif isinstance(v, function):
34	n/a	methods.append(k)
35	n/a	for m in methods:
36	n/a	pre = dict.get("%s_pre" % m)
37	n/a	post = dict.get("%s_post" % m)
38	n/a	if pre or post:
39	n/a	dict[m] = cls.make_eiffel_method(dict[m], pre, post)
40	n/a
41	n/a
42	n/a	class EiffelMetaClass1(EiffelBaseMetaClass):
43	n/a	# an implementation of the "eiffel" meta class that uses nested functions
44	n/a
45	n/a	@staticmethod
46	n/a	def make_eiffel_method(func, pre, post):
47	n/a	def method(self, args, *kwargs):
48	n/a	if pre:
49	n/a	pre(self, args, *kwargs)
50	n/a	rv = func(self, args, *kwargs)
51	n/a	if post:
52	n/a	post(self, rv, args, *kwargs)
53	n/a	return rv
54	n/a
55	n/a	if func.__doc__:
56	n/a	method.__doc__ = func.__doc__
57	n/a
58	n/a	return method
59	n/a
60	n/a
61	n/a	class EiffelMethodWrapper:
62	n/a
63	n/a	def __init__(self, inst, descr):
64	n/a	self._inst = inst
65	n/a	self._descr = descr
66	n/a
67	n/a	def __call__(self, args, *kwargs):
68	n/a	return self._descr.callmethod(self._inst, args, kwargs)
69	n/a
70	n/a
71	n/a	class EiffelDescriptor:
72	n/a
73	n/a	def __init__(self, func, pre, post):
74	n/a	self._func = func
75	n/a	self._pre = pre
76	n/a	self._post = post
77	n/a
78	n/a	self.__name__ = func.__name__
79	n/a	self.__doc__ = func.__doc__
80	n/a
81	n/a	def __get__(self, obj, cls):
82	n/a	return EiffelMethodWrapper(obj, self)
83	n/a
84	n/a	def callmethod(self, inst, args, kwargs):
85	n/a	if self._pre:
86	n/a	self._pre(inst, args, *kwargs)
87	n/a	x = self._func(inst, args, *kwargs)
88	n/a	if self._post:
89	n/a	self._post(inst, x, args, *kwargs)
90	n/a	return x
91	n/a
92	n/a
93	n/a	class EiffelMetaClass2(EiffelBaseMetaClass):
94	n/a	# an implementation of the "eiffel" meta class that uses descriptors
95	n/a
96	n/a	make_eiffel_method = EiffelDescriptor
97	n/a
98	n/a
99	n/a	class Tests(unittest.TestCase):
100	n/a
101	n/a	def testEiffelMetaClass1(self):
102	n/a	self._test(EiffelMetaClass1)
103	n/a
104	n/a	def testEiffelMetaClass2(self):
105	n/a	self._test(EiffelMetaClass2)
106	n/a
107	n/a	def _test(self, metaclass):
108	n/a	class Eiffel(metaclass=metaclass):
109	n/a	pass
110	n/a
111	n/a	class Test(Eiffel):
112	n/a	def m(self, arg):
113	n/a	"""Make it a little larger"""
114	n/a	return arg + 1
115	n/a
116	n/a	def m2(self, arg):
117	n/a	"""Make it a little larger"""
118	n/a	return arg + 1
119	n/a
120	n/a	def m2_pre(self, arg):
121	n/a	assert arg > 0
122	n/a
123	n/a	def m2_post(self, result, arg):
124	n/a	assert result > arg
125	n/a
126	n/a	class Sub(Test):
127	n/a	def m2(self, arg):
128	n/a	return arg**2
129	n/a
130	n/a	def m2_post(self, Result, arg):
131	n/a	super(Sub, self).m2_post(Result, arg)
132	n/a	assert Result < 100
133	n/a
134	n/a	t = Test()
135	n/a	self.assertEqual(t.m(1), 2)
136	n/a	self.assertEqual(t.m2(1), 2)
137	n/a	self.assertRaises(AssertionError, t.m2, 0)
138	n/a
139	n/a	s = Sub()
140	n/a	self.assertRaises(AssertionError, s.m2, 1)
141	n/a	self.assertRaises(AssertionError, s.m2, 10)
142	n/a	self.assertEqual(s.m2(5), 25)
143	n/a
144	n/a
145	n/a	if __name__ == "__main__":
146	n/a	unittest.main()