On Tue, Nov 20, 2012 at 9:44 AM, Nick Coghlan <ncogh...@gmail.com> wrote:
> On Tue, Nov 20, 2012 at 11:45 PM, Christian Tismer > <tis...@stackless.com>wrote: > >> On 20.11.12 12:39, Nick Coghlan wrote: >> >> On Tue, Nov 20, 2012 at 7:06 PM, Kristján Valur Jónsson < >> krist...@ccpgames.com> wrote: >> >>> I’m intrigued. I thought this was merely so that one could do >>> >>> python –m mypackage.mysubpackage >>> >>> Can you refer me to the rationale and discussion about this feature? >>> >> >> It was part of a fairly long progression in changes to the command line >> execution support :) >> >> Top level package execution with -m came first in 2.4, arbitrary package >> execution for -m arrived in 2.5 (along with the runpy module), directory >> and zipfile execution (by supplying a valid sys.path entry as the "script" >> command line argument) was added in 2.6/3.0, and finally officially >> supported package execution via -m only arrived in 2.7 and 3.1 (a broken >> version of the last accidentally existed in 2.5, but that was just a >> mistake that arose when merging the import emulations in runpy and pkgutil, >> and had a side effect that violated at least one of the import system >> invariants). >> >> In the specific case of directory and zipfile execution, discussion >> happened on the tracker: http://bugs.python.org/issue1739468 >> >> It was never brought up on python-dev because Guido was participating >> directly in the tracker discussion. Unfortunately, we then also forgot to >> mention it in the original version of the 2.6 What's New doc, so the vast >> majority of people missed the addition :( >> >> >> Hi Nick, >> >> thank you very much for this story and the link to the issue tracker! >> A very good move for Python which is really not mentioned enough >> to make people more aware of a great feature. >> >> I think part of this discussion should get a more prominent place >> for gems that can be found without knowing what to search. ;-) >> > > Technically, that's the "using" guide: > http://docs.python.org/2/using/cmdline.html#interface-options (see the > explanation of what's executable under the "<script>" tag) > > I also wrote up a summary last year on my blog: > http://www.boredomandlaziness.org/2011/03/what-is-python-script.html > > (The main change since that post is that the Python launcher brings > shebang line support to Windows, although I haven't checked if it works > properly with prefixed zip files) > > Maybe I should plan to sign up to present an updated version of my PyCon > AU 2010 "What is a Python script?" lightning talk at PyCon US 2013 :) > > >> Is the issue tracker permanent enough to reference it? >> > > I've been referencing that particular issue for years now, so I certainly > think so :) > > >> Maybe there could be some auxiliary info page with proper keywords >> that collects links to relevant discussions like this. >> Do we have such a thing already? >> > > I've sometimes thought it may be a good idea to split out a separate "What > is a Python script?" section in the using guide, separate from the existing > descriptions under the interpreter options. I've never tried to figure out > the details of how that would actually work, though. > The wheel projects' own wheel file (a zip file) takes advantage of this feature in its own way: python wheel-0.14.0-py2.py3-none-any.whl/wheel Python looks inside the /wheel directory of the zip file, finds __main__.py, and executes it; the archive can be used to install itself or any other wheel file. (There is no __main__.py at the root because the wheel design would install that __main__.py into the root of site-packages). This underutilized feature of executing directories with __main__.py is very useful for implementing Python applications instead of just libraries. It might be interesting to define a "wheels" format which would be a bunch of unpacked wheel files and a __main__.py like: __main__.py package1-x86.whl/... package1-armel.whl/... package2-noarch.whl/ __main__.py would add the appropriate packages to PYTHONPATH based on the architecture, unpack dll's pkg_resources style, and run the program. There is some activity in the tracker about adding the missing "add this to PYTHONPATH" / "isolate self from the environment" command line arguments to Python. Daniel Holth
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