"""functools.py - Tools for working with functions and callable objects | |
""" | |
# 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> | |
# Copyright (C) 2006 Python Software Foundation. | |
# See C source code for _functools credits/copyright | |
from _functools import partial, reduce | |
# update_wrapper() and wraps() are tools to help write | |
# wrapper functions that can handle naive introspection | |
WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__') | |
WRAPPER_UPDATES = ('__dict__',) | |
def update_wrapper(wrapper, | |
wrapped, | |
assigned = WRAPPER_ASSIGNMENTS, | |
updated = WRAPPER_UPDATES): | |
"""Update a wrapper function to look like the wrapped function | |
wrapper is the function to be updated | |
wrapped is the original function | |
assigned is a tuple naming the attributes assigned directly | |
from the wrapped function to the wrapper function (defaults to | |
functools.WRAPPER_ASSIGNMENTS) | |
updated is a tuple naming the attributes of the wrapper that | |
are updated with the corresponding attribute from the wrapped | |
function (defaults to functools.WRAPPER_UPDATES) | |
""" | |
for attr in assigned: | |
setattr(wrapper, attr, getattr(wrapped, attr)) | |
for attr in updated: | |
getattr(wrapper, attr).update(getattr(wrapped, attr, {})) | |
# Return the wrapper so this can be used as a decorator via partial() | |
return wrapper | |
def wraps(wrapped, | |
assigned = WRAPPER_ASSIGNMENTS, | |
updated = WRAPPER_UPDATES): | |
"""Decorator factory to apply update_wrapper() to a wrapper function | |
Returns a decorator that invokes update_wrapper() with the decorated | |
function as the wrapper argument and the arguments to wraps() as the | |
remaining arguments. Default arguments are as for update_wrapper(). | |
This is a convenience function to simplify applying partial() to | |
update_wrapper(). | |
""" | |
return partial(update_wrapper, wrapped=wrapped, | |
assigned=assigned, updated=updated) | |
def total_ordering(cls): | |
"""Class decorator that fills in missing ordering methods""" | |
convert = { | |
'__lt__': [('__gt__', lambda self, other: not (self < other or self == other)), | |
('__le__', lambda self, other: self < other or self == other), | |
('__ge__', lambda self, other: not self < other)], | |
'__le__': [('__ge__', lambda self, other: not self <= other or self == other), | |
('__lt__', lambda self, other: self <= other and not self == other), | |
('__gt__', lambda self, other: not self <= other)], | |
'__gt__': [('__lt__', lambda self, other: not (self > other or self == other)), | |
('__ge__', lambda self, other: self > other or self == other), | |
('__le__', lambda self, other: not self > other)], | |
'__ge__': [('__le__', lambda self, other: (not self >= other) or self == other), | |
('__gt__', lambda self, other: self >= other and not self == other), | |
('__lt__', lambda self, other: not self >= other)] | |
} | |
roots = set(dir(cls)) & set(convert) | |
if not roots: | |
raise ValueError('must define at least one ordering operation: < > <= >=') | |
root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__ | |
for opname, opfunc in convert[root]: | |
if opname not in roots: | |
opfunc.__name__ = opname | |
opfunc.__doc__ = getattr(int, opname).__doc__ | |
setattr(cls, opname, opfunc) | |
return cls | |
def cmp_to_key(mycmp): | |
"""Convert a cmp= function into a key= function""" | |
class K(object): | |
__slots__ = ['obj'] | |
def __init__(self, obj, *args): | |
self.obj = obj | |
def __lt__(self, other): | |
return mycmp(self.obj, other.obj) < 0 | |
def __gt__(self, other): | |
return mycmp(self.obj, other.obj) > 0 | |
def __eq__(self, other): | |
return mycmp(self.obj, other.obj) == 0 | |
def __le__(self, other): | |
return mycmp(self.obj, other.obj) <= 0 | |
def __ge__(self, other): | |
return mycmp(self.obj, other.obj) >= 0 | |
def __ne__(self, other): | |
return mycmp(self.obj, other.obj) != 0 | |
def __hash__(self): | |
raise TypeError('hash not implemented') | |
return K |