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mtime property throws exception writable GzipFile instances #160860
Description
Bug report
>>> g = gzip.open(io.BytesIO(), "wb", mtime=1234567)
>>> g.mtime
AttributeError: '_WriteBufferStream' object has no attribute '_last_mtime'Instead of an exception, I believe it should reflect the value passed to the constructor.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Activity
pythongh-160860: Fix value of GzipFIle.mtime of writable stream
aisk commentedon Oct 29, 2026
I think you mean
gzip.open(io.BytesIO(), 'wb', mtime=1234567)?On main that raises
AttributeError: '_WriteBufferStream' object has no attribute '_last_mtime'rather than returning None.jepler commentedon Oct 29, 2026
yesssssss. What you describe is what I initially saw. I re-tested as I wrote this issue and saw
Noneinstead. As you realized, it's because I lostmode="wb"in the open call. I'll fix the title & initial comment. Thanks.[-]`mtime` is None for writable `GzipFile` instances[/-][+]`mtime` property throws exception writable `GzipFile` instances[/+]