pythonfunctools。totalordering用法

　　目的
　　让类支持比较操作。
　　介绍
　　在不使用functools.total_ordering时，需要支持__lt__、__le__、__gt__、__ge__、__eq__、__ne__这些方法，才能保证类具有常用的比较操作。
　　通过查看functools.total_ordering源码发现，如果是实现了__lt__，那么程序会自动帮你实现了__gt__， __ge__，__lt__函数。
　　源码如下_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)] }
　　用法
　　不使用functools.total_orderingclass Circle(object):          def __init__(self, radio):         self.radio = radio          @property     def area(self):         import math         return math.pi * (self.radio * self.radio)          def __lt__(self, circle):         return self.area < circle.area          def __le__(self, circle):         return self.area <= circle.area          def __gt__(self, circle):         return self.area > circle.area          def __ge__(self, circle):         return self.area >= circle.area          def __eq__(self, circle):         return self.area == circle.area          def __ne__(self, circle):         return self.area != circle.area           c1 = Circle(10) c2 = Circle(20) print(c1 == c2) print(c1 != c2) print(c1 >= c2) print(c1 <= c2) print(c1 > c2) print(c1 < c2)  #-------- output -------- # False # True # False # True # False # True
　　使用functools.total_orderingfrom functools import total_ordering   @total_ordering class Circle(object):          def __init__(self, radio):         self.radio = radio          @property     def area(self):         import math         return math.pi * (self.radio * self.radio)          def __lt__(self, circle):         return self.area < circle.area          def __eq__(self, circle):         return self.area == circle.area          def __ne__(self, circle):         return self.area != circle.area           c1 = Circle(10) c2 = Circle(20) print(c1 == c2) print(c1 != c2) print(c1 >= c2) print(c1 <= c2) print(c1 > c2) print(c1 < c2)  #-------- output -------- # False # True # False # True # False # True