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- """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
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