定制自己的数据类型

Posted 2020-09-13 study_python

#继承
"""
class LIST(list):
    def append(self, p_object):
        if not isinstance(p_object,int):
            raise TypeError(‘must be int‘)
        super().append(p_object)

    def insert(self, index, p_object):
        if not isinstance(p_object,int):
            raise TypeError(‘must be int‘)
        super().insert(index,p_object)

li =LIST([1,2,3])
print(li)
#li.append(‘2‘)
li.append(4)
print(li)
li.insert(0,-10)
print(li)
#li.insert(0,‘-1‘)
print(li)
"""
#授权
import time
class Open:
    def __init__(self,filepath,m=‘w+‘,encode=‘utf-8‘):
        self.filepath =filepath
        self.mode =m
        self.encoding =encode
        self.x =open(filepath,mode =m,encoding=encode)
    def write(self,line):
        t =time.strftime(‘%Y-%m-%d %X‘)
        self.x.write(‘%s  %s‘%(t,line))


    def __getattr__(self, item):
        print(‘%s %s‘%(self,item))#getattr(self.x,item),中的item是字符串
        return getattr(self.x,item)#把它转化成self.x.item(属性),
        #print(‘%s  %s‘(self))
f =Open(‘a‘)
f.write(‘12112121\n‘)
f.write(‘121212121\n‘)
f.seek(0)
print(f.read)#查询f.read,但是没有找到,f.read,所以就触发__getattr__方法