Python之组合的方式完成授权

初步模型

class Open():
    def __init__(self,filename,mode = "r",encoding  = "utf-8"):
        # self.filename = filename
        self.file = open(filename,mode,encoding=encoding)
        self.mode = mode
        self.encoding = encoding

    def __getattr__(self, item):
        # print(item,type(item))
        #self.file.read
        return getattr(self.file,item) #把f1传给self，把read传给item，因此这里边getattr是，相当于通过文件句柄self.file调用他的相关方法
                            #get的f1.file下的read方法
f1 = Open("a.txt","w")
print(f1.__dict__)
print(f1.file)
print("==>",f1.read)  #因为类里没有read方法，所以触发__getattr__

sys_f = open("b.txt","w+")
print("-->",getattr(sys_f,"read"))

#结果
{'file': <_io.TextIOWrapper name='a.txt' mode='w' encoding='utf-8'>, 'mode': 'w', 'encoding': 'utf-8'}
<_io.TextIOWrapper name='a.txt' mode='w' encoding='utf-8'>
==> <built-in method read of _io.TextIOWrapper object at 0x00000000001AAC18>
--> <built-in method read of _io.TextIOWrapper object at 0x0000000001E92048>
```8