Feature or enhancement

Proposal:

Currently, tarfile.open() doesn't support specifying a compression level / preset when using mode="w|xz". Technically this is documented (via not listing w|xz among the modes supporting either compresslevel or preset argument), it's kinda surprising (to the point of me thinking that w|xz takes compresslevel instead of preset, since the latter threw a TypeError — and then being surprised that the default compression level was used), and quite limiting that you can't set the preset while using stream mode. On top of that, there does not seem to be any technical limitation preventing us from doing that.

I'm working on a pull request to add that option.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-133005: Support tarfile.open(mode="w|xz", preset=...) #133007