| _orig_open = open | |
| class _BkFile: | |
| def __init__(self, file, mode, bufsize): | |
| import os | |
| self.__filename = file | |
| self.__backup = file + '~' | |
| try: | |
| os.unlink(self.__backup) | |
| except os.error: | |
| pass | |
| try: | |
| os.rename(file, self.__backup) | |
| except os.error: | |
| self.__backup = None | |
| self.__file = _orig_open(file, mode, bufsize) | |
| self.closed = self.__file.closed | |
| self.fileno = self.__file.fileno | |
| self.flush = self.__file.flush | |
| self.isatty = self.__file.isatty | |
| self.mode = self.__file.mode | |
| self.name = self.__file.name | |
| self.read = self.__file.read | |
| self.readinto = self.__file.readinto | |
| self.readline = self.__file.readline | |
| self.readlines = self.__file.readlines | |
| self.seek = self.__file.seek | |
| self.softspace = self.__file.softspace | |
| self.tell = self.__file.tell | |
| self.truncate = self.__file.truncate | |
| self.write = self.__file.write | |
| self.writelines = self.__file.writelines | |
| def close(self): | |
| self.__file.close() | |
| if self.__backup is None: | |
| return | |
| import filecmp | |
| if filecmp.cmp(self.__backup, self.__filename, shallow = 0): | |
| import os | |
| os.unlink(self.__filename) | |
| os.rename(self.__backup, self.__filename) | |
| def open(file, mode = 'r', bufsize = -1): | |
| if 'w' not in mode: | |
| return _orig_open(file, mode, bufsize) | |
| return _BkFile(file, mode, bufsize) |