Issue #27137: align Python & C implementations of functools.partial
The pure Python fallback implementation of functools.partial now matches the behaviour of its accelerated C counterpart for subclassing, pickling and text representation purposes. Patch by Emanuel Barry and Serhiy Storchaka.
This commit is contained in:
Nick Coghlan
parent
eddc4b7272
commit
457fc9a69e
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@ -21,6 +21,7 @@ from abc import get_cache_token
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from collections import namedtuple
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from types import MappingProxyType
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from weakref import WeakKeyDictionary
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from reprlib import recursive_repr
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try:
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from _thread import RLock
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except ImportError:
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@ -237,11 +238,24 @@ except ImportError:
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################################################################################
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# Purely functional, no descriptor behaviour
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def partial(func, *args, **keywords):
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class partial:
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"""New function with partial application of the given arguments
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and keywords.
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"""
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if hasattr(func, 'func'):
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__slots__ = "func", "args", "keywords", "__dict__", "__weakref__"
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def __new__(*args, **keywords):
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if not args:
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raise TypeError("descriptor '__new__' of partial needs an argument")
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if len(args) < 2:
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raise TypeError("type 'partial' takes at least one argument")
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cls, func, *args = args
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if not callable(func):
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raise TypeError("the first argument must be callable")
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args = tuple(args)
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if hasattr(func, "func"):
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args = func.args + args
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tmpkw = func.keywords.copy()
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tmpkw.update(keywords)
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@ -249,14 +263,58 @@ def partial(func, *args, **keywords):
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del tmpkw
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func = func.func
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def newfunc(*fargs, **fkeywords):
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newkeywords = keywords.copy()
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newkeywords.update(fkeywords)
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return func(*(args + fargs), **newkeywords)
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newfunc.func = func
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newfunc.args = args
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newfunc.keywords = keywords
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return newfunc
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self = super(partial, cls).__new__(cls)
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self.func = func
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self.args = args
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self.keywords = keywords
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return self
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def __call__(*args, **keywords):
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if not args:
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raise TypeError("descriptor '__call__' of partial needs an argument")
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self, *args = args
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newkeywords = self.keywords.copy()
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newkeywords.update(keywords)
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return self.func(*self.args, *args, **newkeywords)
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@recursive_repr()
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def __repr__(self):
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qualname = type(self).__qualname__
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args = [repr(self.func)]
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args.extend(repr(x) for x in self.args)
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args.extend(f"{k}={v!r}" for (k, v) in self.keywords.items())
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if type(self).__module__ == "functools":
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return f"functools.{qualname}({', '.join(args)})"
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return f"{qualname}({', '.join(args)})"
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def __reduce__(self):
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return type(self), (self.func,), (self.func, self.args,
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self.keywords or None, self.__dict__ or None)
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def __setstate__(self, state):
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if not isinstance(state, tuple):
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raise TypeError("argument to __setstate__ must be a tuple")
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if len(state) != 4:
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raise TypeError(f"expected 4 items in state, got {len(state)}")
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func, args, kwds, namespace = state
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if (not callable(func) or not isinstance(args, tuple) or
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(kwds is not None and not isinstance(kwds, dict)) or
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(namespace is not None and not isinstance(namespace, dict))):
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raise TypeError("invalid partial state")
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args = tuple(args) # just in case it's a subclass
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if kwds is None:
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kwds = {}
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elif type(kwds) is not dict: # XXX does it need to be *exactly* dict?
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kwds = dict(kwds)
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if namespace is None:
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namespace = {}
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self.__dict__ = namespace
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self.func = func
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self.args = args
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self.keywords = kwds
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try:
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from _functools import partial
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@ -8,6 +8,7 @@ import sys
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from test import support
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import unittest
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from weakref import proxy
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import contextlib
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try:
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import threading
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except ImportError:
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@ -20,6 +21,14 @@ c_functools = support.import_fresh_module('functools', fresh=['_functools'])
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decimal = support.import_fresh_module('decimal', fresh=['_decimal'])
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@contextlib.contextmanager
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def replaced_module(name, replacement):
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original_module = sys.modules[name]
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sys.modules[name] = replacement
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try:
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yield
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finally:
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sys.modules[name] = original_module
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def capture(*args, **kw):
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"""capture all positional and keyword arguments"""
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@ -167,58 +176,35 @@ class TestPartial:
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p2.new_attr = 'spam'
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self.assertEqual(p2.new_attr, 'spam')
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@unittest.skipUnless(c_functools, 'requires the C _functools module')
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class TestPartialC(TestPartial, unittest.TestCase):
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if c_functools:
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partial = c_functools.partial
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def test_attributes_unwritable(self):
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# attributes should not be writable
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p = self.partial(capture, 1, 2, a=10, b=20)
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self.assertRaises(AttributeError, setattr, p, 'func', map)
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self.assertRaises(AttributeError, setattr, p, 'args', (1, 2))
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self.assertRaises(AttributeError, setattr, p, 'keywords', dict(a=1, b=2))
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p = self.partial(hex)
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try:
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del p.__dict__
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except TypeError:
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pass
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else:
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self.fail('partial object allowed __dict__ to be deleted')
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def test_repr(self):
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args = (object(), object())
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args_repr = ', '.join(repr(a) for a in args)
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kwargs = {'a': object(), 'b': object()}
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kwargs_reprs = ['a={a!r}, b={b!r}'.format_map(kwargs),
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'b={b!r}, a={a!r}'.format_map(kwargs)]
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if self.partial is c_functools.partial:
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if self.partial in (c_functools.partial, py_functools.partial):
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name = 'functools.partial'
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else:
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name = self.partial.__name__
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f = self.partial(capture)
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self.assertEqual('{}({!r})'.format(name, capture),
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repr(f))
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self.assertEqual(f'{name}({capture!r})', repr(f))
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f = self.partial(capture, *args)
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self.assertEqual('{}({!r}, {})'.format(name, capture, args_repr),
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repr(f))
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self.assertEqual(f'{name}({capture!r}, {args_repr})', repr(f))
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f = self.partial(capture, **kwargs)
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self.assertIn(repr(f),
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['{}({!r}, {})'.format(name, capture, kwargs_repr)
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[f'{name}({capture!r}, {kwargs_repr})'
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for kwargs_repr in kwargs_reprs])
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f = self.partial(capture, *args, **kwargs)
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self.assertIn(repr(f),
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['{}({!r}, {}, {})'.format(name, capture, args_repr, kwargs_repr)
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[f'{name}({capture!r}, {args_repr}, {kwargs_repr})'
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for kwargs_repr in kwargs_reprs])
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def test_recursive_repr(self):
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if self.partial is c_functools.partial:
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if self.partial in (c_functools.partial, py_functools.partial):
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name = 'functools.partial'
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else:
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name = self.partial.__name__
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@ -226,25 +212,26 @@ class TestPartialC(TestPartial, unittest.TestCase):
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f = self.partial(capture)
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f.__setstate__((f, (), {}, {}))
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try:
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self.assertEqual(repr(f), '%s(%s(...))' % (name, name))
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self.assertEqual(repr(f), '%s(...)' % (name,))
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finally:
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f.__setstate__((capture, (), {}, {}))
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f = self.partial(capture)
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f.__setstate__((capture, (f,), {}, {}))
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try:
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self.assertEqual(repr(f), '%s(%r, %s(...))' % (name, capture, name))
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self.assertEqual(repr(f), '%s(%r, ...)' % (name, capture,))
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finally:
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f.__setstate__((capture, (), {}, {}))
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f = self.partial(capture)
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f.__setstate__((capture, (), {'a': f}, {}))
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try:
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self.assertEqual(repr(f), '%s(%r, a=%s(...))' % (name, capture, name))
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self.assertEqual(repr(f), '%s(%r, a=...)' % (name, capture,))
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finally:
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f.__setstate__((capture, (), {}, {}))
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def test_pickle(self):
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with self.AllowPickle():
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f = self.partial(signature, ['asdf'], bar=[True])
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f.attr = []
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for proto in range(pickle.HIGHEST_PROTOCOL + 1):
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@ -274,11 +261,13 @@ class TestPartialC(TestPartial, unittest.TestCase):
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def test_setstate(self):
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f = self.partial(signature)
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f.__setstate__((capture, (1,), dict(a=10), dict(attr=[])))
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self.assertEqual(signature(f),
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(capture, (1,), dict(a=10), dict(attr=[])))
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self.assertEqual(f(2, b=20), ((1, 2), {'a': 10, 'b': 20}))
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f.__setstate__((capture, (1,), dict(a=10), None))
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self.assertEqual(signature(f), (capture, (1,), dict(a=10), {}))
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self.assertEqual(f(2, b=20), ((1, 2), {'a': 10, 'b': 20}))
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@ -325,6 +314,7 @@ class TestPartialC(TestPartial, unittest.TestCase):
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self.assertIs(type(r[0]), tuple)
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def test_recursive_pickle(self):
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with self.AllowPickle():
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f = self.partial(capture)
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f.__setstate__((f, (), {}, {}))
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try:
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@ -375,24 +365,60 @@ class TestPartialC(TestPartial, unittest.TestCase):
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f = self.partial(object)
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self.assertRaises(TypeError, f.__setstate__, BadSequence())
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@unittest.skipUnless(c_functools, 'requires the C _functools module')
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class TestPartialC(TestPartial, unittest.TestCase):
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if c_functools:
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partial = c_functools.partial
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class AllowPickle:
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def __enter__(self):
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return self
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def __exit__(self, type, value, tb):
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return False
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def test_attributes_unwritable(self):
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# attributes should not be writable
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p = self.partial(capture, 1, 2, a=10, b=20)
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self.assertRaises(AttributeError, setattr, p, 'func', map)
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self.assertRaises(AttributeError, setattr, p, 'args', (1, 2))
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self.assertRaises(AttributeError, setattr, p, 'keywords', dict(a=1, b=2))
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p = self.partial(hex)
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try:
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del p.__dict__
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except TypeError:
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pass
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else:
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self.fail('partial object allowed __dict__ to be deleted')
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class TestPartialPy(TestPartial, unittest.TestCase):
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partial = staticmethod(py_functools.partial)
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partial = py_functools.partial
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class AllowPickle:
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def __init__(self):
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self._cm = replaced_module("functools", py_functools)
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def __enter__(self):
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return self._cm.__enter__()
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def __exit__(self, type, value, tb):
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return self._cm.__exit__(type, value, tb)
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if c_functools:
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class PartialSubclass(c_functools.partial):
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class CPartialSubclass(c_functools.partial):
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pass
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class PyPartialSubclass(py_functools.partial):
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pass
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@unittest.skipUnless(c_functools, 'requires the C _functools module')
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class TestPartialCSubclass(TestPartialC):
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if c_functools:
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partial = PartialSubclass
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partial = CPartialSubclass
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# partial subclasses are not optimized for nested calls
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test_nested_optimization = None
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class TestPartialPySubclass(TestPartialPy):
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partial = PyPartialSubclass
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class TestPartialMethod(unittest.TestCase):
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@ -683,9 +709,10 @@ class TestWraps(TestUpdateWrapper):
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self.assertEqual(wrapper.attr, 'This is a different test')
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self.assertEqual(wrapper.dict_attr, f.dict_attr)
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@unittest.skipUnless(c_functools, 'requires the C _functools module')
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class TestReduce(unittest.TestCase):
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func = functools.reduce
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if c_functools:
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func = c_functools.reduce
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def test_reduce(self):
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class Squares:
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@ -135,6 +135,11 @@ Core and Builtins
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Library
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-------
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- Issue #27137: the pure Python fallback implementation of ``functools.partial``
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now matches the behaviour of its accelerated C counterpart for subclassing,
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pickling and text representation purposes. Patch by Emanuel Barry and
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Serhiy Storchaka.
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- Issue #28019: itertools.count() no longer rounds non-integer step in range
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between 1.0 and 2.0 to 1.
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@ -229,7 +229,7 @@ partial_repr(partialobject *pto)
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if (status != 0) {
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if (status < 0)
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return NULL;
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return PyUnicode_FromFormat("%s(...)", Py_TYPE(pto)->tp_name);
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return PyUnicode_FromString("...");
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}
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arglist = PyUnicode_FromString("");
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