File test_singledispatch.py of Package python-singledispatch.14914
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
import collections
import decimal
from itertools import permutations
import singledispatch as functools
from singledispatch_helpers import Support
try:
from collections import ChainMap
except ImportError:
from singledispatch_helpers import ChainMap
collections.ChainMap = ChainMap
try:
from collections import OrderedDict
except ImportError:
from singledispatch_helpers import OrderedDict
collections.OrderedDict = OrderedDict
try:
import unittest2 as unittest
except ImportError:
import unittest
support = Support()
for _prefix in ('collections.abc', '_abcoll'):
if _prefix in repr(collections.Container):
abcoll_prefix = _prefix
break
else:
abcoll_prefix = '?'
del _prefix
class TestSingleDispatch(unittest.TestCase):
def test_simple_overloads(self):
@functools.singledispatch
def g(obj):
return "base"
def g_int(i):
return "integer"
g.register(int, g_int)
self.assertEqual(g("str"), "base")
self.assertEqual(g(1), "integer")
self.assertEqual(g([1,2,3]), "base")
def test_mro(self):
@functools.singledispatch
def g(obj):
return "base"
class A(object):
pass
class C(A):
pass
class B(A):
pass
class D(C, B):
pass
def g_A(a):
return "A"
def g_B(b):
return "B"
g.register(A, g_A)
g.register(B, g_B)
self.assertEqual(g(A()), "A")
self.assertEqual(g(B()), "B")
self.assertEqual(g(C()), "A")
self.assertEqual(g(D()), "B")
def test_register_decorator(self):
@functools.singledispatch
def g(obj):
return "base"
@g.register(int)
def g_int(i):
return "int %s" % (i,)
self.assertEqual(g(""), "base")
self.assertEqual(g(12), "int 12")
self.assertIs(g.dispatch(int), g_int)
self.assertIs(g.dispatch(object), g.dispatch(str))
# Note: in the assert above this is not g.
# @singledispatch returns the wrapper.
def test_wrapping_attributes(self):
@functools.singledispatch
def g(obj):
"Simple test"
return "Test"
self.assertEqual(g.__name__, "g")
self.assertEqual(g.__doc__, "Simple test")
@unittest.skipUnless(decimal, 'requires _decimal')
@support.cpython_only
def test_c_classes(self):
@functools.singledispatch
def g(obj):
return "base"
@g.register(decimal.DecimalException)
def _(obj):
return obj.args
subn = decimal.Subnormal("Exponent < Emin")
rnd = decimal.Rounded("Number got rounded")
self.assertEqual(g(subn), ("Exponent < Emin",))
self.assertEqual(g(rnd), ("Number got rounded",))
@g.register(decimal.Subnormal)
def _(obj):
return "Too small to care."
self.assertEqual(g(subn), "Too small to care.")
self.assertEqual(g(rnd), ("Number got rounded",))
def test_compose_mro(self):
# None of the examples in this test depend on haystack ordering.
c = collections
mro = functools._compose_mro
bases = [c.Sequence, c.MutableMapping, c.Mapping, c.Set]
for haystack in permutations(bases):
m = mro(dict, haystack)
self.assertEqual(m, [dict, c.MutableMapping, c.Mapping, c.Sized,
c.Iterable, c.Container, object])
bases = [c.Container, c.Mapping, c.MutableMapping, c.OrderedDict]
for haystack in permutations(bases):
m = mro(c.ChainMap, haystack)
self.assertEqual(m, [c.ChainMap, c.MutableMapping, c.Mapping,
c.Sized, c.Iterable, c.Container, object])
# If there's a generic function with implementations registered for
# both Sized and Container, passing a defaultdict to it results in an
# ambiguous dispatch which will cause a RuntimeError (see
# test_mro_conflicts).
bases = [c.Container, c.Sized, str]
for haystack in permutations(bases):
m = mro(c.defaultdict, [c.Sized, c.Container, str])
self.assertEqual(m, [c.defaultdict, dict, c.Sized, c.Container,
object])
# MutableSequence below is registered directly on D. In other words, it
# preceeds MutableMapping which means single dispatch will always
# choose MutableSequence here.
class D(c.defaultdict):
pass
c.MutableSequence.register(D)
bases = [c.MutableSequence, c.MutableMapping]
for haystack in permutations(bases):
m = mro(D, bases)
self.assertEqual(m, [D, c.MutableSequence, c.Sequence,
c.defaultdict, dict, c.MutableMapping,
c.Mapping, c.Sized, c.Iterable, c.Container,
object])
# Container and Callable are registered on different base classes and
# a generic function supporting both should always pick the Callable
# implementation if a C instance is passed.
class C(c.defaultdict):
def __call__(self):
pass
bases = [c.Sized, c.Callable, c.Container, c.Mapping]
for haystack in permutations(bases):
m = mro(C, haystack)
self.assertEqual(m, [C, c.Callable, c.defaultdict, dict, c.Mapping,
c.Sized, c.Iterable, c.Container, object])
def test_register_abc(self):
c = collections
d = {"a": "b"}
l = [1, 2, 3]
s = set([object(), None])
f = frozenset(s)
t = (1, 2, 3)
@functools.singledispatch
def g(obj):
return "base"
self.assertEqual(g(d), "base")
self.assertEqual(g(l), "base")
self.assertEqual(g(s), "base")
self.assertEqual(g(f), "base")
self.assertEqual(g(t), "base")
g.register(c.Sized, lambda obj: "sized")
self.assertEqual(g(d), "sized")
self.assertEqual(g(l), "sized")
self.assertEqual(g(s), "sized")
self.assertEqual(g(f), "sized")
self.assertEqual(g(t), "sized")
g.register(c.MutableMapping, lambda obj: "mutablemapping")
self.assertEqual(g(d), "mutablemapping")
self.assertEqual(g(l), "sized")
self.assertEqual(g(s), "sized")
self.assertEqual(g(f), "sized")
self.assertEqual(g(t), "sized")
g.register(c.ChainMap, lambda obj: "chainmap")
self.assertEqual(g(d), "mutablemapping") # irrelevant ABCs registered
self.assertEqual(g(l), "sized")
self.assertEqual(g(s), "sized")
self.assertEqual(g(f), "sized")
self.assertEqual(g(t), "sized")
g.register(c.MutableSequence, lambda obj: "mutablesequence")
self.assertEqual(g(d), "mutablemapping")
self.assertEqual(g(l), "mutablesequence")
self.assertEqual(g(s), "sized")
self.assertEqual(g(f), "sized")
self.assertEqual(g(t), "sized")
g.register(c.MutableSet, lambda obj: "mutableset")
self.assertEqual(g(d), "mutablemapping")
self.assertEqual(g(l), "mutablesequence")
self.assertEqual(g(s), "mutableset")
self.assertEqual(g(f), "sized")
self.assertEqual(g(t), "sized")
g.register(c.Mapping, lambda obj: "mapping")
self.assertEqual(g(d), "mutablemapping") # not specific enough
self.assertEqual(g(l), "mutablesequence")
self.assertEqual(g(s), "mutableset")
self.assertEqual(g(f), "sized")
self.assertEqual(g(t), "sized")
g.register(c.Sequence, lambda obj: "sequence")
self.assertEqual(g(d), "mutablemapping")
self.assertEqual(g(l), "mutablesequence")
self.assertEqual(g(s), "mutableset")
self.assertEqual(g(f), "sized")
self.assertEqual(g(t), "sequence")
g.register(c.Set, lambda obj: "set")
self.assertEqual(g(d), "mutablemapping")
self.assertEqual(g(l), "mutablesequence")
self.assertEqual(g(s), "mutableset")
self.assertEqual(g(f), "set")
self.assertEqual(g(t), "sequence")
g.register(dict, lambda obj: "dict")
self.assertEqual(g(d), "dict")
self.assertEqual(g(l), "mutablesequence")
self.assertEqual(g(s), "mutableset")
self.assertEqual(g(f), "set")
self.assertEqual(g(t), "sequence")
g.register(list, lambda obj: "list")
self.assertEqual(g(d), "dict")
self.assertEqual(g(l), "list")
self.assertEqual(g(s), "mutableset")
self.assertEqual(g(f), "set")
self.assertEqual(g(t), "sequence")
g.register(set, lambda obj: "concrete-set")
self.assertEqual(g(d), "dict")
self.assertEqual(g(l), "list")
self.assertEqual(g(s), "concrete-set")
self.assertEqual(g(f), "set")
self.assertEqual(g(t), "sequence")
g.register(frozenset, lambda obj: "frozen-set")
self.assertEqual(g(d), "dict")
self.assertEqual(g(l), "list")
self.assertEqual(g(s), "concrete-set")
self.assertEqual(g(f), "frozen-set")
self.assertEqual(g(t), "sequence")
g.register(tuple, lambda obj: "tuple")
self.assertEqual(g(d), "dict")
self.assertEqual(g(l), "list")
self.assertEqual(g(s), "concrete-set")
self.assertEqual(g(f), "frozen-set")
self.assertEqual(g(t), "tuple")
def test_c3_abc(self):
c = collections
mro = functools._c3_mro
class A(object):
pass
class B(A):
def __len__(self):
return 0 # implies Sized
#@c.Container.register
class C(object):
pass
c.Container.register(C)
class D(object):
pass # unrelated
class X(D, C, B):
def __call__(self):
pass # implies Callable
expected = [X, c.Callable, D, C, c.Container, B, c.Sized, A, object]
for abcs in permutations([c.Sized, c.Callable, c.Container]):
self.assertEqual(mro(X, abcs=abcs), expected)
# unrelated ABCs don't appear in the resulting MRO
many_abcs = [c.Mapping, c.Sized, c.Callable, c.Container, c.Iterable]
self.assertEqual(mro(X, abcs=many_abcs), expected)
def test_mro_conflicts(self):
c = collections
@functools.singledispatch
def g(arg):
return "base"
class O(c.Sized):
def __len__(self):
return 0
o = O()
self.assertEqual(g(o), "base")
g.register(c.Iterable, lambda arg: "iterable")
g.register(c.Container, lambda arg: "container")
g.register(c.Sized, lambda arg: "sized")
g.register(c.Set, lambda arg: "set")
self.assertEqual(g(o), "sized")
c.Iterable.register(O)
self.assertEqual(g(o), "sized") # because it's explicitly in __mro__
c.Container.register(O)
self.assertEqual(g(o), "sized") # see above: Sized is in __mro__
c.Set.register(O)
self.assertEqual(g(o), "set") # because c.Set is a subclass of
# c.Sized and c.Container
class P(object):
pass
p = P()
self.assertEqual(g(p), "base")
c.Iterable.register(P)
self.assertEqual(g(p), "iterable")
c.Container.register(P)
with self.assertRaises(RuntimeError) as re_one:
g(p)
self.assertIn(
str(re_one.exception),
(("Ambiguous dispatch: <class '{prefix}.Container'> "
"or <class '{prefix}.Iterable'>").format(prefix=abcoll_prefix),
("Ambiguous dispatch: <class '{prefix}.Iterable'> "
"or <class '{prefix}.Container'>").format(prefix=abcoll_prefix)),
)
class Q(c.Sized):
def __len__(self):
return 0
q = Q()
self.assertEqual(g(q), "sized")
c.Iterable.register(Q)
self.assertEqual(g(q), "sized") # because it's explicitly in __mro__
c.Set.register(Q)
self.assertEqual(g(q), "set") # because c.Set is a subclass of
# c.Sized and c.Iterable
@functools.singledispatch
def h(arg):
return "base"
@h.register(c.Sized)
def _(arg):
return "sized"
@h.register(c.Container)
def _(arg):
return "container"
# Even though Sized and Container are explicit bases of MutableMapping,
# this ABC is implicitly registered on defaultdict which makes all of
# MutableMapping's bases implicit as well from defaultdict's
# perspective.
with self.assertRaises(RuntimeError) as re_two:
h(c.defaultdict(lambda: 0))
self.assertIn(
str(re_two.exception),
(("Ambiguous dispatch: <class '{prefix}.Container'> "
"or <class '{prefix}.Sized'>").format(prefix=abcoll_prefix),
("Ambiguous dispatch: <class '{prefix}.Sized'> "
"or <class '{prefix}.Container'>").format(prefix=abcoll_prefix)),
)
class R(c.defaultdict):
pass
c.MutableSequence.register(R)
@functools.singledispatch
def i(arg):
return "base"
@i.register(c.MutableMapping)
def _(arg):
return "mapping"
@i.register(c.MutableSequence)
def _(arg):
return "sequence"
r = R()
self.assertEqual(i(r), "sequence")
class S(object):
pass
class T(S, c.Sized):
def __len__(self):
return 0
t = T()
self.assertEqual(h(t), "sized")
c.Container.register(T)
self.assertEqual(h(t), "sized") # because it's explicitly in the MRO
class U(object):
def __len__(self):
return 0
u = U()
self.assertEqual(h(u), "sized") # implicit Sized subclass inferred
# from the existence of __len__()
c.Container.register(U)
# There is no preference for registered versus inferred ABCs.
with self.assertRaises(RuntimeError) as re_three:
h(u)
self.assertIn(
str(re_three.exception),
(("Ambiguous dispatch: <class '{prefix}.Container'> "
"or <class '{prefix}.Sized'>").format(prefix=abcoll_prefix),
("Ambiguous dispatch: <class '{prefix}.Sized'> "
"or <class '{prefix}.Container'>").format(prefix=abcoll_prefix)),
)
class V(c.Sized, S):
def __len__(self):
return 0
@functools.singledispatch
def j(arg):
return "base"
@j.register(S)
def _(arg):
return "s"
@j.register(c.Container)
def _(arg):
return "container"
v = V()
self.assertEqual(j(v), "s")
c.Container.register(V)
self.assertEqual(j(v), "container") # because it ends up right after
# Sized in the MRO
def test_cache_invalidation(self):
try:
from collections import UserDict
except ImportError:
from UserDict import UserDict
class TracingDict(UserDict):
def __init__(self, *args, **kwargs):
UserDict.__init__(self, *args, **kwargs)
self.set_ops = []
self.get_ops = []
def __getitem__(self, key):
result = self.data[key]
self.get_ops.append(key)
return result
def __setitem__(self, key, value):
self.set_ops.append(key)
self.data[key] = value
def clear(self):
self.data.clear()
_orig_wkd = functools.WeakKeyDictionary
td = TracingDict()
functools.WeakKeyDictionary = lambda: td
c = collections
@functools.singledispatch
def g(arg):
return "base"
d = {}
l = []
self.assertEqual(len(td), 0)
self.assertEqual(g(d), "base")
self.assertEqual(len(td), 1)
self.assertEqual(td.get_ops, [])
self.assertEqual(td.set_ops, [dict])
self.assertEqual(td.data[dict], g.registry[object])
self.assertEqual(g(l), "base")
self.assertEqual(len(td), 2)
self.assertEqual(td.get_ops, [])
self.assertEqual(td.set_ops, [dict, list])
self.assertEqual(td.data[dict], g.registry[object])
self.assertEqual(td.data[list], g.registry[object])
self.assertEqual(td.data[dict], td.data[list])
self.assertEqual(g(l), "base")
self.assertEqual(g(d), "base")
self.assertEqual(td.get_ops, [list, dict])
self.assertEqual(td.set_ops, [dict, list])
g.register(list, lambda arg: "list")
self.assertEqual(td.get_ops, [list, dict])
self.assertEqual(len(td), 0)
self.assertEqual(g(d), "base")
self.assertEqual(len(td), 1)
self.assertEqual(td.get_ops, [list, dict])
self.assertEqual(td.set_ops, [dict, list, dict])
self.assertEqual(td.data[dict],
functools._find_impl(dict, g.registry))
self.assertEqual(g(l), "list")
self.assertEqual(len(td), 2)
self.assertEqual(td.get_ops, [list, dict])
self.assertEqual(td.set_ops, [dict, list, dict, list])
self.assertEqual(td.data[list],
functools._find_impl(list, g.registry))
class X(object):
pass
c.MutableMapping.register(X) # Will not invalidate the cache,
# not using ABCs yet.
self.assertEqual(g(d), "base")
self.assertEqual(g(l), "list")
self.assertEqual(td.get_ops, [list, dict, dict, list])
self.assertEqual(td.set_ops, [dict, list, dict, list])
g.register(c.Sized, lambda arg: "sized")
self.assertEqual(len(td), 0)
self.assertEqual(g(d), "sized")
self.assertEqual(len(td), 1)
self.assertEqual(td.get_ops, [list, dict, dict, list])
self.assertEqual(td.set_ops, [dict, list, dict, list, dict])
self.assertEqual(g(l), "list")
self.assertEqual(len(td), 2)
self.assertEqual(td.get_ops, [list, dict, dict, list])
self.assertEqual(td.set_ops, [dict, list, dict, list, dict, list])
self.assertEqual(g(l), "list")
self.assertEqual(g(d), "sized")
self.assertEqual(td.get_ops, [list, dict, dict, list, list, dict])
self.assertEqual(td.set_ops, [dict, list, dict, list, dict, list])
g.dispatch(list)
g.dispatch(dict)
self.assertEqual(td.get_ops, [list, dict, dict, list, list, dict,
list, dict])
self.assertEqual(td.set_ops, [dict, list, dict, list, dict, list])
c.MutableSet.register(X) # Will invalidate the cache.
self.assertEqual(len(td), 2) # Stale cache.
self.assertEqual(g(l), "list")
self.assertEqual(len(td), 1)
g.register(c.MutableMapping, lambda arg: "mutablemapping")
self.assertEqual(len(td), 0)
self.assertEqual(g(d), "mutablemapping")
self.assertEqual(len(td), 1)
self.assertEqual(g(l), "list")
self.assertEqual(len(td), 2)
g.register(dict, lambda arg: "dict")
self.assertEqual(g(d), "dict")
self.assertEqual(g(l), "list")
g._clear_cache()
self.assertEqual(len(td), 0)
functools.WeakKeyDictionary = _orig_wkd
if __name__ == '__main__':
unittest.main()
