[Python-checkins] cpython: Add reference implementation for PEP 443
lukasz.langa
python-checkins at python.org
Wed Jun 5 12:20:49 CEST 2013
http://hg.python.org/cpython/rev/dfcb64f51f7b
changeset: 84039:dfcb64f51f7b
user: Łukasz Langa <lukasz at langa.pl>
date: Wed Jun 05 12:20:24 2013 +0200
summary:
Add reference implementation for PEP 443
PEP accepted: http://mail.python.org/pipermail/python-dev/2013-June/126734.html
files:
Doc/library/functools.rst | 110 +++++++
Lib/functools.py | 128 ++++++++-
Lib/pkgutil.py | 52 +---
Lib/test/test_functools.py | 374 ++++++++++++++++++++++++-
Misc/NEWS | 3 +
Modules/Setup.dist | 2 +-
6 files changed, 614 insertions(+), 55 deletions(-)
diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst
--- a/Doc/library/functools.rst
+++ b/Doc/library/functools.rst
@@ -6,6 +6,7 @@
.. moduleauthor:: Peter Harris <scav at blueyonder.co.uk>
.. moduleauthor:: Raymond Hettinger <python at rcn.com>
.. moduleauthor:: Nick Coghlan <ncoghlan at gmail.com>
+.. moduleauthor:: Łukasz Langa <lukasz at langa.pl>
.. sectionauthor:: Peter Harris <scav at blueyonder.co.uk>
**Source code:** :source:`Lib/functools.py`
@@ -186,6 +187,115 @@
*sequence* contains only one item, the first item is returned.
+.. decorator:: singledispatch(default)
+
+ Transforms a function into a single-dispatch generic function. A **generic
+ function** is composed of multiple functions implementing the same operation
+ for different types. Which implementation should be used during a call is
+ determined by the dispatch algorithm. When the implementation is chosen
+ based on the type of a single argument, this is known as **single
+ dispatch**.
+
+ To define a generic function, decorate it with the ``@singledispatch``
+ decorator. Note that the dispatch happens on the type of the first argument,
+ create your function accordingly::
+
+ >>> from functools import singledispatch
+ >>> @singledispatch
+ ... def fun(arg, verbose=False):
+ ... if verbose:
+ ... print("Let me just say,", end=" ")
+ ... print(arg)
+
+ To add overloaded implementations to the function, use the :func:`register`
+ attribute of the generic function. It is a decorator, taking a type
+ parameter and decorating a function implementing the operation for that
+ type::
+
+ >>> @fun.register(int)
+ ... def _(arg, verbose=False):
+ ... if verbose:
+ ... print("Strength in numbers, eh?", end=" ")
+ ... print(arg)
+ ...
+ >>> @fun.register(list)
+ ... def _(arg, verbose=False):
+ ... if verbose:
+ ... print("Enumerate this:")
+ ... for i, elem in enumerate(arg):
+ ... print(i, elem)
+
+ To enable registering lambdas and pre-existing functions, the
+ :func:`register` attribute can be used in a functional form::
+
+ >>> def nothing(arg, verbose=False):
+ ... print("Nothing.")
+ ...
+ >>> fun.register(type(None), nothing)
+
+ The :func:`register` attribute returns the undecorated function which
+ enables decorator stacking, pickling, as well as creating unit tests for
+ each variant independently::
+
+ >>> @fun.register(float)
+ ... @fun.register(Decimal)
+ ... def fun_num(arg, verbose=False):
+ ... if verbose:
+ ... print("Half of your number:", end=" ")
+ ... print(arg / 2)
+ ...
+ >>> fun_num is fun
+ False
+
+ When called, the generic function dispatches on the type of the first
+ argument::
+
+ >>> fun("Hello, world.")
+ Hello, world.
+ >>> fun("test.", verbose=True)
+ Let me just say, test.
+ >>> fun(42, verbose=True)
+ Strength in numbers, eh? 42
+ >>> fun(['spam', 'spam', 'eggs', 'spam'], verbose=True)
+ Enumerate this:
+ 0 spam
+ 1 spam
+ 2 eggs
+ 3 spam
+ >>> fun(None)
+ Nothing.
+ >>> fun(1.23)
+ 0.615
+
+ Where there is no registered implementation for a specific type, its
+ method resolution order is used to find a more generic implementation.
+ The original function decorated with ``@singledispatch`` is registered
+ for the base ``object`` type, which means it is used if no better
+ implementation is found.
+
+ To check which implementation will the generic function choose for
+ a given type, use the ``dispatch()`` attribute::
+
+ >>> fun.dispatch(float)
+ <function fun_num at 0x1035a2840>
+ >>> fun.dispatch(dict) # note: default implementation
+ <function fun at 0x103fe0000>
+
+ To access all registered implementations, use the read-only ``registry``
+ attribute::
+
+ >>> fun.registry.keys()
+ dict_keys([<class 'NoneType'>, <class 'int'>, <class 'object'>,
+ <class 'decimal.Decimal'>, <class 'list'>,
+ <class 'float'>])
+ >>> fun.registry[float]
+ <function fun_num at 0x1035a2840>
+ >>> fun.registry[object]
+ <function fun at 0x103fe0000>
+
+ .. versionadded:: 3.4
+
+
.. function:: update_wrapper(wrapper, wrapped, assigned=WRAPPER_ASSIGNMENTS, updated=WRAPPER_UPDATES)
Update a *wrapper* function to look like the *wrapped* function. The optional
diff --git a/Lib/functools.py b/Lib/functools.py
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -3,19 +3,24 @@
# Python module wrapper for _functools C module
# to allow utilities written in Python to be added
# to the functools module.
-# Written by Nick Coghlan <ncoghlan at gmail.com>
-# and Raymond Hettinger <python at rcn.com>
-# Copyright (C) 2006-2010 Python Software Foundation.
+# Written by Nick Coghlan <ncoghlan at gmail.com>,
+# Raymond Hettinger <python at rcn.com>,
+# and Łukasz Langa <lukasz at langa.pl>.
+# Copyright (C) 2006-2013 Python Software Foundation.
# See C source code for _functools credits/copyright
__all__ = ['update_wrapper', 'wraps', 'WRAPPER_ASSIGNMENTS', 'WRAPPER_UPDATES',
- 'total_ordering', 'cmp_to_key', 'lru_cache', 'reduce', 'partial']
+ 'total_ordering', 'cmp_to_key', 'lru_cache', 'reduce', 'partial',
+ 'singledispatch']
try:
from _functools import reduce
except ImportError:
pass
+from abc import get_cache_token
from collections import namedtuple
+from types import MappingProxyType
+from weakref import WeakKeyDictionary
try:
from _thread import RLock
except:
@@ -354,3 +359,118 @@
return update_wrapper(wrapper, user_function)
return decorating_function
+
+
+################################################################################
+### singledispatch() - single-dispatch generic function decorator
+################################################################################
+
+def _compose_mro(cls, haystack):
+ """Calculates the MRO for a given class `cls`, including relevant abstract
+ base classes from `haystack`.
+
+ """
+ bases = set(cls.__mro__)
+ mro = list(cls.__mro__)
+ for needle in haystack:
+ if (needle in bases or not hasattr(needle, '__mro__')
+ or not issubclass(cls, needle)):
+ continue # either present in the __mro__ already or unrelated
+ for index, base in enumerate(mro):
+ if not issubclass(base, needle):
+ break
+ if base in bases and not issubclass(needle, base):
+ # Conflict resolution: put classes present in __mro__ and their
+ # subclasses first. See test_mro_conflicts() in test_functools.py
+ # for examples.
+ index += 1
+ mro.insert(index, needle)
+ return mro
+
+def _find_impl(cls, registry):
+ """Returns the best matching implementation for the given class `cls` in
+ `registry`. Where there is no registered implementation for a specific
+ type, its method resolution order is used to find a more generic
+ implementation.
+
+ Note: if `registry` does not contain an implementation for the base
+ `object` type, this function may return None.
+
+ """
+ mro = _compose_mro(cls, registry.keys())
+ match = None
+ for t in mro:
+ if match is not None:
+ # If `match` is an ABC but there is another unrelated, equally
+ # matching ABC. Refuse the temptation to guess.
+ if (t in registry and not issubclass(match, t)
+ and match not in cls.__mro__):
+ raise RuntimeError("Ambiguous dispatch: {} or {}".format(
+ match, t))
+ break
+ if t in registry:
+ match = t
+ return registry.get(match)
+
+def singledispatch(func):
+ """Single-dispatch generic function decorator.
+
+ Transforms a function into a generic function, which can have different
+ behaviours depending upon the type of its first argument. The decorated
+ function acts as the default implementation, and additional
+ implementations can be registered using the 'register()' attribute of
+ the generic function.
+
+ """
+ registry = {}
+ dispatch_cache = WeakKeyDictionary()
+ cache_token = None
+
+ def dispatch(typ):
+ """generic_func.dispatch(type) -> <function implementation>
+
+ Runs the dispatch algorithm to return the best available implementation
+ for the given `type` registered on `generic_func`.
+
+ """
+ nonlocal cache_token
+ if cache_token is not None:
+ current_token = get_cache_token()
+ if cache_token != current_token:
+ dispatch_cache.clear()
+ cache_token = current_token
+ try:
+ impl = dispatch_cache[typ]
+ except KeyError:
+ try:
+ impl = registry[typ]
+ except KeyError:
+ impl = _find_impl(typ, registry)
+ dispatch_cache[typ] = impl
+ return impl
+
+ def register(typ, func=None):
+ """generic_func.register(type, func) -> func
+
+ Registers a new implementation for the given `type` on a `generic_func`.
+
+ """
+ nonlocal cache_token
+ if func is None:
+ return lambda f: register(typ, f)
+ registry[typ] = func
+ if cache_token is None and hasattr(typ, '__abstractmethods__'):
+ cache_token = get_cache_token()
+ dispatch_cache.clear()
+ return func
+
+ def wrapper(*args, **kw):
+ return dispatch(args[0].__class__)(*args, **kw)
+
+ registry[object] = func
+ wrapper.register = register
+ wrapper.dispatch = dispatch
+ wrapper.registry = MappingProxyType(registry)
+ wrapper._clear_cache = dispatch_cache.clear
+ update_wrapper(wrapper, func)
+ return wrapper
diff --git a/Lib/pkgutil.py b/Lib/pkgutil.py
--- a/Lib/pkgutil.py
+++ b/Lib/pkgutil.py
@@ -1,12 +1,13 @@
"""Utilities to support packages."""
+from functools import singledispatch as simplegeneric
+import imp
+import importlib
import os
+import os.path
import sys
-import importlib
-import imp
-import os.path
+from types import ModuleType
from warnings import warn
-from types import ModuleType
__all__ = [
'get_importer', 'iter_importers', 'get_loader', 'find_loader',
@@ -27,46 +28,6 @@
return marshal.load(stream)
-def simplegeneric(func):
- """Make a trivial single-dispatch generic function"""
- registry = {}
- def wrapper(*args, **kw):
- ob = args[0]
- try:
- cls = ob.__class__
- except AttributeError:
- cls = type(ob)
- try:
- mro = cls.__mro__
- except AttributeError:
- try:
- class cls(cls, object):
- pass
- mro = cls.__mro__[1:]
- except TypeError:
- mro = object, # must be an ExtensionClass or some such :(
- for t in mro:
- if t in registry:
- return registry[t](*args, **kw)
- else:
- return func(*args, **kw)
- try:
- wrapper.__name__ = func.__name__
- except (TypeError, AttributeError):
- pass # Python 2.3 doesn't allow functions to be renamed
-
- def register(typ, func=None):
- if func is None:
- return lambda f: register(typ, f)
- registry[typ] = func
- return func
-
- wrapper.__dict__ = func.__dict__
- wrapper.__doc__ = func.__doc__
- wrapper.register = register
- return wrapper
-
-
def walk_packages(path=None, prefix='', onerror=None):
"""Yields (module_loader, name, ispkg) for all modules recursively
on path, or, if path is None, all accessible modules.
@@ -148,13 +109,12 @@
yield i, name, ispkg
-#@simplegeneric
+ at simplegeneric
def iter_importer_modules(importer, prefix=''):
if not hasattr(importer, 'iter_modules'):
return []
return importer.iter_modules(prefix)
-iter_importer_modules = simplegeneric(iter_importer_modules)
# Implement a file walker for the normal importlib path hook
def _iter_file_finder_modules(importer, prefix=''):
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -1,24 +1,30 @@
import collections
-import sys
-import unittest
-from test import support
-from weakref import proxy
+from itertools import permutations
import pickle
from random import choice
+import sys
+from test import support
+import unittest
+from weakref import proxy
import functools
py_functools = support.import_fresh_module('functools', blocked=['_functools'])
c_functools = support.import_fresh_module('functools', fresh=['_functools'])
+decimal = support.import_fresh_module('decimal', fresh=['_decimal'])
+
+
def capture(*args, **kw):
"""capture all positional and keyword arguments"""
return args, kw
+
def signature(part):
""" return the signature of a partial object """
return (part.func, part.args, part.keywords, part.__dict__)
+
class TestPartial:
def test_basic_examples(self):
@@ -138,6 +144,7 @@
join = self.partial(''.join)
self.assertEqual(join(data), '0123456789')
+
@unittest.skipUnless(c_functools, 'requires the C _functools module')
class TestPartialC(TestPartial, unittest.TestCase):
if c_functools:
@@ -194,18 +201,22 @@
"new style getargs format but argument is not a tuple",
f.__setstate__, BadSequence())
+
class TestPartialPy(TestPartial, unittest.TestCase):
partial = staticmethod(py_functools.partial)
+
if c_functools:
class PartialSubclass(c_functools.partial):
pass
+
@unittest.skipUnless(c_functools, 'requires the C _functools module')
class TestPartialCSubclass(TestPartialC):
if c_functools:
partial = PartialSubclass
+
class TestUpdateWrapper(unittest.TestCase):
def check_wrapper(self, wrapper, wrapped,
@@ -312,6 +323,7 @@
self.assertTrue(wrapper.__doc__.startswith('max('))
self.assertEqual(wrapper.__annotations__, {})
+
class TestWraps(TestUpdateWrapper):
def _default_update(self):
@@ -372,6 +384,7 @@
self.assertEqual(wrapper.attr, 'This is a different test')
self.assertEqual(wrapper.dict_attr, f.dict_attr)
+
class TestReduce(unittest.TestCase):
func = functools.reduce
@@ -452,6 +465,7 @@
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(self.func(add, d), "".join(d.keys()))
+
class TestCmpToKey:
def test_cmp_to_key(self):
@@ -534,14 +548,17 @@
self.assertRaises(TypeError, hash, k)
self.assertNotIsInstance(k, collections.Hashable)
+
@unittest.skipUnless(c_functools, 'requires the C _functools module')
class TestCmpToKeyC(TestCmpToKey, unittest.TestCase):
if c_functools:
cmp_to_key = c_functools.cmp_to_key
+
class TestCmpToKeyPy(TestCmpToKey, unittest.TestCase):
cmp_to_key = staticmethod(py_functools.cmp_to_key)
+
class TestTotalOrdering(unittest.TestCase):
def test_total_ordering_lt(self):
@@ -642,6 +659,7 @@
with self.assertRaises(TypeError):
TestTO(8) <= ()
+
class TestLRU(unittest.TestCase):
def test_lru(self):
@@ -834,6 +852,353 @@
DoubleEq(2)) # Verify the correct return value
+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 C:
+ pass
+ class D(C):
+ pass
+ def g_C(c):
+ return "C"
+ g.register(C, g_C)
+ self.assertEqual(g(C()), "C")
+ self.assertEqual(g(D()), "C")
+
+ def test_classic_classes(self):
+ @functools.singledispatch
+ def g(obj):
+ return "base"
+ class C:
+ pass
+ class D(C):
+ pass
+ def g_C(c):
+ return "C"
+ g.register(C, g_C)
+ self.assertEqual(g(C()), "C")
+ self.assertEqual(g(D()), "C")
+
+ 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):
+ 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, 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])
+ # Note: The MRO order below depends on haystack ordering.
+ m = mro(c.defaultdict, [c.Sized, c.Container, str])
+ self.assertEqual(m, [c.defaultdict, dict, c.Container, c.Sized, object])
+ m = mro(c.defaultdict, [c.Container, c.Sized, str])
+ self.assertEqual(m, [c.defaultdict, dict, c.Sized, c.Container, object])
+
+ def test_register_abc(self):
+ c = collections
+ d = {"a": "b"}
+ l = [1, 2, 3]
+ s = {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_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__
+
+ class P:
+ 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:
+ g(p)
+ self.assertEqual(
+ str(re),
+ ("Ambiguous dispatch: <class 'collections.abc.Container'> "
+ "or <class 'collections.abc.Iterable'>"),
+ )
+
+ 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 which is explicitly in
+ # __mro__
+
+ def test_cache_invalidation(self):
+ from collections import UserDict
+ class TracingDict(UserDict):
+ def __init__(self, *args, **kwargs):
+ super(TracingDict, self).__init__(*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:
+ 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
+
+
def test_main(verbose=None):
test_classes = (
TestPartialC,
@@ -846,6 +1211,7 @@
TestWraps,
TestReduce,
TestLRU,
+ TestSingleDispatch,
)
support.run_unittest(*test_classes)
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -344,6 +344,9 @@
the default for linking if LDSHARED is not also overriden. This restores
Distutils behavior introduced in 3.2.3 and inadvertently dropped in 3.3.0.
+- Implement PEP 443 "Single-dispatch generic functions".
+
+
Tests
-----
diff --git a/Modules/Setup.dist b/Modules/Setup.dist
--- a/Modules/Setup.dist
+++ b/Modules/Setup.dist
@@ -116,6 +116,7 @@
_operator _operator.c # operator.add() and similar goodies
_collections _collectionsmodule.c # Container types
itertools itertoolsmodule.c # Functions creating iterators for efficient looping
+atexit atexitmodule.c # Register functions to be run at interpreter-shutdown
# access to ISO C locale support
_locale _localemodule.c # -lintl
@@ -170,7 +171,6 @@
#_weakref _weakref.c # basic weak reference support
#_testcapi _testcapimodule.c # Python C API test module
#_random _randommodule.c # Random number generator
-#atexit atexitmodule.c # Register functions to be run at interpreter-shutdown
#_elementtree -I$(srcdir)/Modules/expat -DHAVE_EXPAT_CONFIG_H -DUSE_PYEXPAT_CAPI _elementtree.c # elementtree accelerator
#_pickle _pickle.c # pickle accelerator
#_datetime _datetimemodule.c # datetime accelerator
--
Repository URL: http://hg.python.org/cpython
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