sorted 在python2和3中的區別

sorted 在python2和3中的區別

python3中取消了cmp參數

python3中的使用方法如下:

from functools import cmp_to_key

def my_cmp(i1, i2):
    return 1 if i1 < i2 else -1

print(sorted([1, 2, 3], key=cmp_to_key(my_cmp)))

原理如下:

class K(object):
    __slots__ = ['obj']

    def __init__(self, obj):
        self.obj = obj

    def __lt__(self, other):
        return 1

    def __gt__(self, other):
        return 1

    def __eq__(self, other):
        return 1

    def __le__(self, other):
        return 1

    def __ge__(self, other):
        return 1

    __hash__ = None

print(sorted([1, 2, 3], key=K))