[New-bugs-announce] [issue32728] Extend zipfile's compression level support to LZMA

bbayles report at bugs.python.org
Tue Jan 30 11:47:20 EST 2018

New submission from bbayles <bbayles at gmail.com>:

In [1] (issue 21417), support for setting an archive (or its files) compression level was added to the zipfile module.

That currently works for the ZIP_DEFLATED and ZIP_BZIP2 compression methods, but not for ZIP_LZMA. This is because zipfile includes its own implementation of LZMACompressor that hard-codes the default preset's parameters (see also [2]).

It should be possible to extend compression level settings to ZIP_LZMA by making zipfile.LZMACompressor more flexible, i.e. able to accept an LZMA preset. I think this would involve porting the function that translates presets to options (lzma_lzma_preset, see [3]) and passing in those options to lzma.LZMACompressor .

[1] https://bugs.python.org/issue21417
[2] https://github.com/python/cpython/pull/5385
[3] https://git.tukaani.org/?p=xz.git;a=blob;f=src/liblzma/lzma/lzma_encoder_presets.c;hb=HEAD

components: Library (Lib)
messages: 311283
nosy: bbayles
priority: normal
severity: normal
status: open
title: Extend zipfile's compression level support  to LZMA
type: enhancement
versions: Python 3.8

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