diff options
Diffstat (limited to 'Lib/functools.py')
-rw-r--r-- | Lib/functools.py | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/Lib/functools.py b/Lib/functools.py index a54f030832..53680b8946 100644 --- a/Lib/functools.py +++ b/Lib/functools.py @@ -49,3 +49,52 @@ def wraps(wrapped, """ 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 |