[Python-Dev] Request for Pronouncement: PEP 441 (original) (raw)

[Python-Dev] Request for Pronouncement: PEP 441 - Improving Python ZIP Application Support

Paul Moore p.f.moore at gmail.com
Tue Feb 24 21:51:00 CET 2015

On 24 February 2015 at 20:32, Barry Warsaw <barry at python.org> wrote:

To modify an archive could be done using

python -m zipapp old.pyz new.pyz [-p interpreter] Default is to strip the shebang (no -p option). There's no option to omit the target and do an inplace update because I feel the default action (strip the shebang from the existing file with no backup) is too dangerous. You have to be careful about the case where old.pyz == new.pyz (e.g. either handling this case safely or complaining loudly) , but also you could handle it by using a .tmp file and renaming. E.g. old.pyz -> old.pyz.bak and old.pyz.tmp -> old.pyz.

There are a lot of obscure failure modes here. What if old and new are symlinks (or hard links) to the same file? What if a .tmp file already exists? What if the user hits Ctrl-C at a bad moment?

On the principle of keeping it simple, I prefer just requiring a target, giving an error if the source name and target name are the same (which still leaves loopholes for the determined fool on case insensitive filesystems :-)) and just documenting that inplace modification isn't supported. The PEP clearly states that it's minimal tooling, after all...

3. What to call the "show the shebang line" option I don't know how useful this is, given that (on *nix at least) you can effectively do the same with head(1).

I don't think it's that useful, TBH (although will head not print binary junk if there is no shebang line?) I quite like Brett's suggestion of --info, and maybe be a bit verbose:

$ python -m zipapp foo.pyz --info Interpreter: /usr/bin/python $ python -m zipapp bar.pyz --info Interpreter:

I can't see it being useful for scripting, and if it matters, there's always get_interpreter() then. It's mainly just as a diagnostic for people who are getting the wrong interpreter invoked.

Paul

More information about the Python-Dev mailing list