相关疑难解决方法(0)

我正在创建一些类来处理各种类型的文件共享(nfs,afp,s3,本地磁盘)等文件名.我得到一个用户输入一个标识数据源(即"nfs://192.168.1.3"或"s3://mybucket/data")等的字符串.

我从具有公共代码的基类继承特定文件系统.我困惑的地方是对象创建.我所拥有的是以下内容:

import os

class FileSystem(object):
    class NoAccess(Exception):
        pass

    def __new__(cls,path):
        if cls is FileSystem:
            if path.upper().startswith('NFS://'): 
                return super(FileSystem,cls).__new__(Nfs)
            else: 
                return super(FileSystem,cls).__new__(LocalDrive)
        else:
            return super(FileSystem,cls).__new__(cls,path)

    def count_files(self):
        raise NotImplementedError

class Nfs(FileSystem):
    def __init__ (self,path):
        pass

    def count_files(self):
        pass

class LocalDrive(FileSystem):
    def __init__(self,path):
        if not os.access(path, os.R_OK):
            raise FileSystem.NoAccess('Cannot read directory')
        self.path = path

    def count_files(self):
        return len([x for x in os.listdir(self.path) if os.path.isfile(os.path.join(self.path, x))])

data1 = FileSystem('nfs://192.168.1.18')
data2 = FileSystem('/var/log')

print type(data1)
print type(data2)

print data2.count_files() …