1 from builtins import open as _orig_open 2 3 def open(file, mode='r', bufsize=-1): 4 if 'w' not in mode: 5 return _orig_open(file, mode, bufsize) 6 import os 7 backup = file + '~' 8 try: 9 os.unlink(backup) 10 except OSError: 11 pass 12 try: 13 os.rename(file, backup) 14 except OSError: 15 return _orig_open(file, mode, bufsize) 16 f = _orig_open(file, mode, bufsize) 17 _orig_close = f.close 18 def close(): 19 _orig_close() 20 import filecmp 21 if filecmp.cmp(backup, file, shallow=False): 22 import os 23 os.unlink(file) 24 os.rename(backup, file) 25 f.close = close 26 return f 27
