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from builtins import open as _orig_open
class _BkFile:
def __init__(self, file, mode, bufsize):
import os
self.__filename = file
self.__backup = file + '~'
try:
os.unlink(self.__backup)
except OSError:
pass
try:
os.rename(file, self.__backup)
except OSError:
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
try:
self.readinto = self.__file.readinto
except AttributeError:
pass
self.readline = self.__file.readline
self.readlines = self.__file.readlines
self.seek = self.__file.seek
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)
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