你知道什么是Python里的鸭子类型和猴子补丁吗？

# 这是一个鸭子(Duck)类
class Duck:
    def __init__(self,name):
        self.name = name
    def swim(self):
        print("A duck named " + self.name+" is swimming...")
    def call(self):
        print("gay...gay...gay...")

# 这是一个鹅（Goose）类
class Goose:
    def __init__(self,name):
        self.name = name
    def swim(self):
        print("A goose named " + self.name+" is swimming...")
    def call(self):
        print("goo...goo...goo...")

# duckshow这个函数设计的本意是需要传入一个Duck对象作为参数的。 
def duckshow(duck):
    duck.swim()
    duck.call()

yaya = Duck("yaya")
ee = Goose("ee")

# 但由于Python是动态语言，其数据类型属于鸭子类型，没有严格类型检查，
# Goose这个类具有和Duck这个类相同的方法，
# ee这只鹅划起水来像只鸭子，叫起来也像一只鸭子，
# 所以duckshow这个函数也可以对ee进行作用。

duckshow(yaya)
duckshow(ee)

A duck named yaya is swimming...
gay ... gay ... gay ...
A goose named ee is swimming...
goo ... goo ... goo ...

# 定义一个Dog类
class Dog:
    def __init__(self,name,age):
        self.name = name
        self.age = age

    def sleep(self):
        print("Zzz...Zzz..Zzz...")

# 在类的外部给Dog这个类添加猴子补丁
def speak(self):
    print("I think myself a hero and very handsome!")

Dog.speak = speak
Dog.home = "Earth"

# 与类的内部定义的属性和方法无差异
snoopy = Dog("snoopy",3)
snoopy.sleep()
snoopy.speak()
print(snoopy.home)

Zzz ... Zzz ... Zzz ...
I think myself a hero and very handsome!
Earth

import numpy as np
import pandas as pd

df = pd.DataFrame(np.random.randint(1,10,size=(5,5)),
                  columns = list("abcde"))
#df.info()
#DataFrame自带方法info打印信息太多，展示不直观。
#给DataFrame定义一个猴子补丁方法memory简洁展示其内存消耗。

def memory(self):
    mem = self.__sizeof__()
    if mem<1024:
        return("%s B"%mem)
    elif mem<1024*1024:
        return("%s KB"%mem/1024)
    elif mem<1024**3:
        return("%s MB"%mem/1024**2)
    else:
        return("%s GB"%mem/1024**3) 

pd.DataFrame.memory = memory

print(df.memory())

280 B