面向对象-鸭子类型

class File:
    def read(self):
        pass

    def write(self):
        pass


class Disk:
    def read(self):
        print(‘disk read‘)

    def write(self):
        print(‘disk write‘)

class Text:
    def read(self):
        print(‘text read‘)
    def write(self):
        print(‘text write‘)

disk=Disk()
text=Text()

disk.read()
disk.write()

text.read()
text.write()


#序列类型：列表list,元组tuple,字符串str

l = list([1, 2, 3])
t=tuple((‘a‘,‘b‘))
s=str(‘hello‘)

print(l.__len__())
print(t.__len__())
print(s.__len__())

def len(obj):
    return obj.__len__()

print(len(l))
print(len(t))
print(len(s))