LearnPython/python_magic_methods.py at master · psvm-enter/LearnPython · GitHub

47 lines (35 loc) · 1.57 KB

# _*_ coding: utf-8 _*_

"""

python_magic_methods.py by xianhu

"""

# 定义一个能够自动比较大小的People类

class People(object):

def __init__(self, name, age):

self.name = name

self.age = age

return

def __str__(self):

return self.name + ":" + str(self.age)

def __lt__(self, other):

return self.name < other.name if self.name != other.name else self.age < other.age

print("\t".join([str(item) for item in sorted([People("abc", 18), People("abe", 19), People("abe", 12), People("abc", 17)])]))

# Python实现任意深度的赋值例如a[0] = 'value1'; a[1][2] = 'value2'; a[3][4][5] = 'value3'

class MyDict(dict):

def __setitem__(self, key, value): # 该函数不做任何改动这里只是为了输出

print("setitem:", key, value, self)

super().__setitem__(key, value)

return

def __getitem__(self, item): # 主要技巧在该函数

print("getitem:", item, self)

# 基本思路: a[1][2]赋值时需要先取出a[1] 然后给a[1]的[2]赋值

if item not in self: # 如果a[1]不存在

temp = MyDict() # 则需要新建一个dict

super().__setitem__(item, temp) # 并使得a[1] = dict

return temp # 返回a[1] 使得a[1][2] = value有效

return super().__getitem__(item) # 如果a[1]存在则直接返回a[1]

# 使用例子:

test = MyDict()

test[0] = 'test'

test[1][2] = 'test1'

test[3][4][5] = 'test2'

print("==========================")

Expand file tree