对象包含的内置方法

class MyObj(object):

def __init__(self):

self.value = 0

myObj = MyObj()

print(dir(myObj))

返回结果

['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'value']

其中和对象比较的内置方法包括：

['__eq__', '__ge__', '__gt__', '__le__', '__lt__', '__ne__']

_convert = {

'__lt__': [('__gt__', _gt_from_lt),

('__le__', _le_from_lt),

('__ge__', _ge_from_lt)],

'__le__': [('__ge__', _ge_from_le),

('__lt__', _lt_from_le),

('__gt__', _gt_from_le)],

'__gt__': [('__lt__', _lt_from_gt),

('__ge__', _ge_from_gt),

('__le__', _le_from_gt)],

'__ge__': [('__le__', _le_from_ge),

('__gt__', _gt_from_ge),

('__lt__', _lt_from_ge)]

}

def total_ordering(cls):

"""Class decorator that fills in missing ordering methods"""

# Find user-defined comparisons (not those inherited from object).

roots = [op for op in _convert if getattr(cls, op, None) is not getattr(object, op, None)]

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

setattr(cls, opname, opfunc)

return cls

这样一来，只要你在定义class的时候加上这个注解，再重写运算符的时候，除了 __eq__和__ne__之外，其他的4个只需要重写一个就可以了，@functools.total_ordering直接就帮你完成了其他比较方法的重写。

@functools.total_ordering

class MyObj(object):

def __init__(self):

self.value = 0

def __eq__(self, other):

self