"safe" file writer implemented as a context manager

backup_file_writer.py

class BackupFileWriter:
    def __init__(self, path, mode='w', prefix='buf-temp-'):
        self.path = path
        self.mode = mode
        self.prefix = prefix
        self.prev = f"{path}.prev"
        self.temp = None
        self.handle = None

    def __enter__(self):
        self.temp = tempfile.mkstemp(prefix=self.prefix, text=True)
        self.handle = os.fdopen(self.temp[0], self.mode)
        if os.path.exists(self.path):
            shutil.copyfile(self.path, self.prev)
        return self.handle

    def __exit__(self, exc_type, exc_val, exc_tb):
        if exc_type is None:
                self.handle.close()
                shutil.copyfile(self.temp[1], self.path)
                os.unlink(self.temp[1])
                return True
        return False