Created
March 29, 2023 21:02
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"safe" file writer implemented as a context manager
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| 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 |
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