_wrapper() - Code Metrics - Inspection of "Merge pull request #12 from adamchainz/readthedocs..." - kalefranz/auxlib - Measure and Improve Code Quality continuously with Scrutinizer

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by Kale

created 2016-10-15 08:49 UTC

_wrapper() C

↳ Parent: memoizemethod()

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	7
c	1
b	0
f	0
dl	0
loc	28
rs	5.5

from __future__ import absolute_import, division, print_function
from collections import Hashable
from types import GeneratorType

from .compat import wraps

# TODO: spend time filling out functionality and make these more robust


def memoize(func):
    """
    Decorator to cause a function to cache it's results for each combination of
    inputs and return the cached result on subsequent calls.  Does not support
    named arguments or arg values that are not hashable.

    >>> @memoize
    ... def foo(x):
    ...     print('running function with', x)
    ...     return x+3
    ...
    >>> foo(10)
    running function with 10
    13
    >>> foo(10)
    13
    >>> foo(11)
    running function with 11
    14
    >>> @memoize
    ... def range_tuple(limit):
    ...     print('running function')
    ...     return tuple(i for i in range(limit))
    ...
    >>> range_tuple(3)
    running function
    (0, 1, 2)
    >>> range_tuple(3)
    (0, 1, 2)
    >>> @memoize
    ... def range_iter(limit):
    ...     print('running function')
    ...     return (i for i in range(limit))
    ...
    >>> range_iter(3)
    Traceback (most recent call last):
    TypeError: Can't memoize a generator or non-hashable object!
    """
    func._result_cache = {}  # pylint: disable-msg=W0212

    @wraps(func)
    def _memoized_func(*args, **kwargs):
        key = (args, tuple(sorted(kwargs.items())))
        if key in func._result_cache:  # pylint: disable-msg=W0212
            return func._result_cache[key]  # pylint: disable-msg=W0212
        else:
            result = func(*args, **kwargs)
            if isinstance(result, GeneratorType) or not isinstance(result, Hashable):
                raise TypeError("Can't memoize a generator or non-hashable object!")
            func._result_cache[key] = result  # pylint: disable-msg=W0212
            return result

    return _memoized_func


def memoizemethod(method):
    """
    Decorator to cause a method to cache it's results in self for each
    combination of inputs and return the cached result on subsequent calls.
    Does not support named arguments or arg values that are not hashable.

    >>> class Foo (object):
    ...   @memoizemethod
    ...   def foo(self, x, y=0):
    ...     print('running method with', x, y)
    ...     return x + y + 3
    ...
    >>> foo1 = Foo()
    >>> foo2 = Foo()
    >>> foo1.foo(10)
    running method with 10 0
    13
    >>> foo1.foo(10)
    13
    >>> foo2.foo(11, y=7)
    running method with 11 7
    21
    >>> foo2.foo(11)
    running method with 11 0
    14
    >>> foo2.foo(11, y=7)
    21
    >>> class Foo (object):
    ...   def __init__(self, lower):
    ...     self.lower = lower
    ...   @memoizemethod
    ...   def range_tuple(self, upper):
    ...     print('running function')
    ...     return tuple(i for i in range(self.lower, upper))
    ...   @memoizemethod
    ...   def range_iter(self, upper):
    ...     print('running function')
    ...     return (i for i in range(self.lower, upper))
    ...
    >>> foo = Foo(3)
    >>> foo.range_tuple(6)
    running function
    (3, 4, 5)
    >>> foo.range_tuple(7)
    running function
    (3, 4, 5, 6)
    >>> foo.range_tuple(6)
    (3, 4, 5)
    >>> foo.range_iter(6)
    Traceback (most recent call last):
    TypeError: Can't memoize a generator or non-hashable object!
    """

    @wraps(method)
    def _wrapper(self, *args, **kwargs):
        # NOTE:  a __dict__ check is performed here rather than using the
        # built-in hasattr function because hasattr will look up to an object's
        # class if the attr is not directly found in the object's dict.  That's
        # bad for this if the class itself has a memoized classmethod for
        # example that has been called before the memoized instance method,
        # then the instance method will use the class's result cache, causing
        # its results to be globally stored rather than on a per instance
        # basis.
        if '_memoized_results' not in self.__dict__:
            self._memoized_results = {}
        memoized_results = self._memoized_results

        key = (method.__name__, args, tuple(sorted(kwargs.items())))
        if key in memoized_results:
            return memoized_results[key]
        else:
            try:
                result = method(self, *args, **kwargs)
            except KeyError as e:
                if '__wrapped__' in str(e):
                    result = None  # is this the right thing to do?  happened during py3 conversion
                else:
                    raise
            if isinstance(result, GeneratorType) or not isinstance(result, Hashable):
                raise TypeError("Can't memoize a generator or non-hashable object!")
            return memoized_results.setdefault(key, result)

    return _wrapper


# class memoizemethod(object):
#     """cache the return value of a method
#
#     This class is meant to be used as a decorator of methods. The return value
#     from a given method invocation will be cached on the instance whose method
#     was invoked. All arguments passed to a method decorated with memoize must
#     be hashable.
#
#     If a memoized method is invoked directly on its class the result will not
#     be cached. Instead the method will be invoked like a static method:
#     class Obj(object):
#         @memoize
#         def add_to(self, arg):
#             return self + arg
#     Obj.add_to(1) # not enough arguments
#     Obj.add_to(1, 2) # returns 3, result is not cached
#     """
#     def __init__(self, func):
#         self.func = func
#     def __get__(self, obj, objtype=None):
#         if obj is None:
#             return self.func
#         return partial(self, obj)
#     def __call__(self, *args, **kw):
#         obj = args[0]
#         try:
#             cache = obj.__cache
#         except AttributeError:
#             cache = obj.__cache = {}
#         key = (self.func, args[1:], frozenset(kw.items()))
#         try:
#             res = cache[key]
#         except KeyError:
#             res = cache[key] = self.func(*args, **kw)
#         return res


def clear_memoized_methods(obj, *method_names):
    """
    Clear the memoized method or @memoizeproperty results for the given
    method names from the given object.

    >>> v = [0]
    >>> def inc():
    ...     v[0] += 1
    ...     return v[0]
    ...
    >>> class Foo(object):
    ...    @memoizemethod
    ...    def foo(self):
    ...        return inc()
    ...    @memoizeproperty
    ...    def g(self):
    ...       return inc()
    ...
    >>> f = Foo()
    >>> f.foo(), f.foo()
    (1, 1)
    >>> clear_memoized_methods(f, 'foo')
    >>> (f.foo(), f.foo(), f.g, f.g)
    (2, 2, 3, 3)
    >>> (f.foo(), f.foo(), f.g, f.g)
    (2, 2, 3, 3)
    >>> clear_memoized_methods(f, 'g', 'no_problem_if_undefined')
    >>> f.g, f.foo(), f.g
    (4, 2, 4)
    >>> f.foo()
    2
    """
    for key in list(getattr(obj, '_memoized_results', {}).keys()):
        # key[0] is the method name
        if key[0] in method_names:
            del obj._memoized_results[key]

    property_dict = obj.__dict__
    for prop in method_names:
        inner_attname = '_{0}'.format(prop)
        if inner_attname in property_dict:
            del property_dict[inner_attname]


def memoizeproperty(func):
    """
    Decorator to cause a method to cache it's results in self for each
    combination of inputs and return the cached result on subsequent calls.
    Does not support named arguments or arg values that are not hashable.

    >>> class Foo (object):
    ...   _x = 1
    ...   @memoizeproperty
    ...   def foo(self):
    ...     self._x += 1
    ...     print('updating and returning {0}'.format(self._x))
    ...     return self._x
    ...
    >>> foo1 = Foo()
    >>> foo2 = Foo()
    >>> foo1.foo
    updating and returning 2
    2
    >>> foo1.foo
    2
    >>> foo2.foo
    updating and returning 2
    2
    >>> foo1.foo
    2
    """
    inner_attname = '_{0}'.format(func.__name__)

    def new_fget(self):
        self_dict = self.__dict__
        if inner_attname not in self_dict:
            self_dict[inner_attname] = func(self)
        return self_dict[inner_attname]

    return property(new_fget)


# def memoized_property(fget):
#     """
#     Return a property attribute for new-style classes that only calls its getter on the first
#     access. The result is stored and on subsequent accesses is returned, preventing the need to
#     call the getter any more.
#     Example::
#         >>> class C(object):
#         ...     load_name_count = 0
#         ...     @memoized_property
#         ...     def name(self):
#         ...         "name's docstring"
#         ...         self.load_name_count += 1
#         ...         return "the name"
#         >>> c = C()
#         >>> c.load_name_count
#         0
#         >>> c.name
#         "the name"
#         >>> c.load_name_count
#         1
#         >>> c.name
#         "the name"
#         >>> c.load_name_count
#         1
#     """
#     attr_name = '_{0}'.format(fget.__name__)
#
#     @wraps(fget)
#     def fget_memoized(self):
#         if not hasattr(self, attr_name):
#             setattr(self, attr_name, fget(self))
#         return getattr(self, attr_name)
#
#     return property(fget_memoized)

class classproperty(object):  # pylint: disable=C0103
    # from celery.five

    def __init__(self, getter=None, setter=None):
        if getter is not None and not isinstance(getter, classmethod):
            getter = classmethod(getter)
        if setter is not None and not isinstance(setter, classmethod):
            setter = classmethod(setter)
        self.__get = getter
        self.__set = setter

        info = getter.__get__(object)  # just need the info attrs.
        self.__doc__ = info.__doc__
        self.__name__ = info.__name__
        self.__module__ = info.__module__

    def __get__(self, obj, type_=None):
        if obj and type_ is None:
            type_ = obj.__class__
        return self.__get.__get__(obj, type_)()

    def __set__(self, obj, value):
        if obj is None:
            return self
        return self.__set.__get__(obj)(value)

    def setter(self, setter):
        return self.__class__(self.__get, setter)

# memoize & clear:
#     class method
#     function
#     classproperty
#     property
#     staticproperty?
# memoizefunction
# memoizemethod
# memoizeproperty
#
#


1			from __future__ import absolute_import, division, print_function
2			from collections import Hashable
3			from types import GeneratorType
4
5			from .compat import wraps
6
7			# TODO: spend time filling out functionality and make these more robust
8
9
10			def memoize(func):
11			"""
12			Decorator to cause a function to cache it's results for each combination of
13			inputs and return the cached result on subsequent calls. Does not support
14			named arguments or arg values that are not hashable.
15
16			>>> @memoize
17			... def foo(x):
18			... print('running function with', x)
19			... return x+3
20			...
21			>>> foo(10)
22			running function with 10
23			13
24			>>> foo(10)
25			13
26			>>> foo(11)
27			running function with 11
28			14
29			>>> @memoize
30			... def range_tuple(limit):
31			... print('running function')
32			... return tuple(i for i in range(limit))
33			...
34			>>> range_tuple(3)
35			running function
36			(0, 1, 2)
37			>>> range_tuple(3)
38			(0, 1, 2)
39			>>> @memoize
40			... def range_iter(limit):
41			... print('running function')
42			... return (i for i in range(limit))
43			...
44			>>> range_iter(3)
45			Traceback (most recent call last):
46			TypeError: Can't memoize a generator or non-hashable object!
47			"""
48			func._result_cache = {} # pylint: disable-msg=W0212
49
50			@wraps(func)
51			def _memoized_func(args, *kwargs):
52			key = (args, tuple(sorted(kwargs.items())))
53			if key in func._result_cache: # pylint: disable-msg=W0212
54			return func._result_cache[key] # pylint: disable-msg=W0212
55			else:
56			result = func(args, *kwargs)
57			if isinstance(result, GeneratorType) or not isinstance(result, Hashable):
58			raise TypeError("Can't memoize a generator or non-hashable object!")
59			func._result_cache[key] = result # pylint: disable-msg=W0212
60			return result
61
62			return _memoized_func
63
64
65			def memoizemethod(method):
66			"""
67			Decorator to cause a method to cache it's results in self for each
68			combination of inputs and return the cached result on subsequent calls.
69			Does not support named arguments or arg values that are not hashable.
70
71			>>> class Foo (object):
72			... @memoizemethod
73			... def foo(self, x, y=0):
74			... print('running method with', x, y)
75			... return x + y + 3
76			...
77			>>> foo1 = Foo()
78			>>> foo2 = Foo()
79			>>> foo1.foo(10)
80			running method with 10 0
81			13
82			>>> foo1.foo(10)
83			13
84			>>> foo2.foo(11, y=7)
85			running method with 11 7
86			21
87			>>> foo2.foo(11)
88			running method with 11 0
89			14
90			>>> foo2.foo(11, y=7)
91			21
92			>>> class Foo (object):
93			... def __init__(self, lower):
94			... self.lower = lower
95			... @memoizemethod
96			... def range_tuple(self, upper):
97			... print('running function')
98			... return tuple(i for i in range(self.lower, upper))
99			... @memoizemethod
100			... def range_iter(self, upper):
101			... print('running function')
102			... return (i for i in range(self.lower, upper))
103			...
104			>>> foo = Foo(3)
105			>>> foo.range_tuple(6)
106			running function
107			(3, 4, 5)
108			>>> foo.range_tuple(7)
109			running function
110			(3, 4, 5, 6)
111			>>> foo.range_tuple(6)
112			(3, 4, 5)
113			>>> foo.range_iter(6)
114			Traceback (most recent call last):
115			TypeError: Can't memoize a generator or non-hashable object!
116			"""
117
118			@wraps(method)
119			def _wrapper(self, args, *kwargs):
120			# NOTE: a __dict__ check is performed here rather than using the
121			# built-in hasattr function because hasattr will look up to an object's
122			# class if the attr is not directly found in the object's dict. That's
123			# bad for this if the class itself has a memoized classmethod for
124			# example that has been called before the memoized instance method,
125			# then the instance method will use the class's result cache, causing
126			# its results to be globally stored rather than on a per instance
127			# basis.
128			if '_memoized_results' not in self.__dict__:
129			self._memoized_results = {}
130			memoized_results = self._memoized_results
131
132			key = (method.__name__, args, tuple(sorted(kwargs.items())))
133			if key in memoized_results:
134			return memoized_results[key]
135			else:
136			try:
137			result = method(self, args, *kwargs)
138			except KeyError as e:
139			if '__wrapped__' in str(e):
140			result = None # is this the right thing to do? happened during py3 conversion
141			else:
142			raise
143			if isinstance(result, GeneratorType) or not isinstance(result, Hashable):
144			raise TypeError("Can't memoize a generator or non-hashable object!")
145			return memoized_results.setdefault(key, result)
146
147			return _wrapper
148
149
150			# class memoizemethod(object):
151			# """cache the return value of a method
152			#
153			# This class is meant to be used as a decorator of methods. The return value
154			# from a given method invocation will be cached on the instance whose method
155			# was invoked. All arguments passed to a method decorated with memoize must
156			# be hashable.
157			#
158			# If a memoized method is invoked directly on its class the result will not
159			# be cached. Instead the method will be invoked like a static method:
160			# class Obj(object):
161			# @memoize
162			# def add_to(self, arg):
163			# return self + arg
164			# Obj.add_to(1) # not enough arguments
165			# Obj.add_to(1, 2) # returns 3, result is not cached
166			# """
167			# def __init__(self, func):
168			# self.func = func
169			# def __get__(self, obj, objtype=None):
170			# if obj is None:
171			# return self.func
172			# return partial(self, obj)
173			# def __call__(self, args, *kw):
174			# obj = args[0]
175			# try:
176			# cache = obj.__cache
177			# except AttributeError:
178			# cache = obj.__cache = {}
179			# key = (self.func, args[1:], frozenset(kw.items()))
180			# try:
181			# res = cache[key]
182			# except KeyError:
183			# res = cache[key] = self.func(args, *kw)
184			# return res
185
186
187			def clear_memoized_methods(obj, *method_names):
188			"""
189			Clear the memoized method or @memoizeproperty results for the given
190			method names from the given object.
191
192			>>> v = [0]
193			>>> def inc():
194			... v[0] += 1
195			... return v[0]
196			...
197			>>> class Foo(object):
198			... @memoizemethod
199			... def foo(self):
200			... return inc()
201			... @memoizeproperty
202			... def g(self):
203			... return inc()
204			...
205			>>> f = Foo()
206			>>> f.foo(), f.foo()
207			(1, 1)
208			>>> clear_memoized_methods(f, 'foo')
209			>>> (f.foo(), f.foo(), f.g, f.g)
210			(2, 2, 3, 3)
211			>>> (f.foo(), f.foo(), f.g, f.g)
212			(2, 2, 3, 3)
213			>>> clear_memoized_methods(f, 'g', 'no_problem_if_undefined')
214			>>> f.g, f.foo(), f.g
215			(4, 2, 4)
216			>>> f.foo()
217			2
218			"""
219			for key in list(getattr(obj, '_memoized_results', {}).keys()):
220			# key[0] is the method name
221			if key[0] in method_names:
222			del obj._memoized_results[key]
223
224			property_dict = obj.__dict__
225			for prop in method_names:
226			inner_attname = '_{0}'.format(prop)
227			if inner_attname in property_dict:
228			del property_dict[inner_attname]
229
230
231			def memoizeproperty(func):
232			"""
233			Decorator to cause a method to cache it's results in self for each
234			combination of inputs and return the cached result on subsequent calls.
235			Does not support named arguments or arg values that are not hashable.
236
237			>>> class Foo (object):
238			... _x = 1
239			... @memoizeproperty
240			... def foo(self):
241			... self._x += 1
242			... print('updating and returning {0}'.format(self._x))
243			... return self._x
244			...
245			>>> foo1 = Foo()
246			>>> foo2 = Foo()
247			>>> foo1.foo
248			updating and returning 2
249			2
250			>>> foo1.foo
251			2
252			>>> foo2.foo
253			updating and returning 2
254			2
255			>>> foo1.foo
256			2
257			"""
258			inner_attname = '_{0}'.format(func.__name__)
259
260			def new_fget(self):
261			self_dict = self.__dict__
262			if inner_attname not in self_dict:
263			self_dict[inner_attname] = func(self)
264			return self_dict[inner_attname]
265
266			return property(new_fget)
267
268
269			# def memoized_property(fget):
270			# """
271			# Return a property attribute for new-style classes that only calls its getter on the first
272			# access. The result is stored and on subsequent accesses is returned, preventing the need to
273			# call the getter any more.
274			# Example::
275			# >>> class C(object):
276			# ... load_name_count = 0
277			# ... @memoized_property
278			# ... def name(self):
279			# ... "name's docstring"
280			# ... self.load_name_count += 1
281			# ... return "the name"
282			# >>> c = C()
283			# >>> c.load_name_count
284			# 0
285			# >>> c.name
286			# "the name"
287			# >>> c.load_name_count
288			# 1
289			# >>> c.name
290			# "the name"
291			# >>> c.load_name_count
292			# 1
293			# """
294			# attr_name = '_{0}'.format(fget.__name__)
295			#
296			# @wraps(fget)
297			# def fget_memoized(self):
298			# if not hasattr(self, attr_name):
299			# setattr(self, attr_name, fget(self))
300			# return getattr(self, attr_name)
301			#
302			# return property(fget_memoized)
303
304			class classproperty(object): # pylint: disable=C0103
305			# from celery.five
306
307			def __init__(self, getter=None, setter=None):
308			if getter is not None and not isinstance(getter, classmethod):
309			getter = classmethod(getter)
310			if setter is not None and not isinstance(setter, classmethod):
311			setter = classmethod(setter)
312			self.__get = getter
313			self.__set = setter
314
315			info = getter.__get__(object) # just need the info attrs.
316			self.__doc__ = info.__doc__
317			self.__name__ = info.__name__
318			self.__module__ = info.__module__
319
320			def __get__(self, obj, type_=None):
321			if obj and type_ is None:
322			type_ = obj.__class__
323			return self.__get.__get__(obj, type_)()
324
325			def __set__(self, obj, value):
326			if obj is None:
327			return self
328			return self.__set.__get__(obj)(value)
329
330			def setter(self, setter):
331			return self.__class__(self.__get, setter)
332
333			# memoize & clear:
334			# class method
335			# function
336			# classproperty
337			# property
338			# staticproperty?
339			# memoizefunction
340			# memoizemethod
341			# memoizeproperty
342			#
343			#
344

kalefranz / auxlib

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_wrapper() C

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