1 from __builtin__ import open as _orig_open 2 3 class _BkFile: 4 def __init__(self, file, mode, bufsize): 5 import os 6 self.__filename = file 7 self.__backup = file + '~' 8 try: 9 os.unlink(self.__backup) 10 except os.error: 11 pass 12 try: 13 os.rename(file, self.__backup) 14 except os.error: 15 self.__backup = None 16 self.__file = _orig_open(file, mode, bufsize) 17 self.closed = self.__file.closed 18 self.fileno = self.__file.fileno 19 self.flush = self.__file.flush 20 self.isatty = self.__file.isatty 21 self.mode = self.__file.mode 22 self.name = self.__file.name 23 self.read = self.__file.read 24 self.readinto = self.__file.readinto 25 self.readline = self.__file.readline 26 self.readlines = self.__file.readlines 27 self.seek = self.__file.seek 28 self.softspace = self.__file.softspace 29 self.tell = self.__file.tell 30 self.truncate = self.__file.truncate 31 self.write = self.__file.write 32 self.writelines = self.__file.writelines 33 34 def close(self): 35 self.__file.close() 36 if self.__backup is None: 37 return 38 import filecmp 39 if filecmp.cmp(self.__backup, self.__filename, shallow = 0): 40 import os 41 os.unlink(self.__filename) 42 os.rename(self.__backup, self.__filename) 43 44 def open(file, mode = 'r', bufsize = -1): 45 if 'w' not in mode: 46 return _orig_open(file, mode, bufsize) 47 return _BkFile(file, mode, bufsize) 48
