<div class="gmail_extra"><div class="gmail_quote">On Tue, Nov 20, 2012 at 9:44 AM, Nick Coghlan <span dir="ltr"><<a href="mailto:ncoghlan@gmail.com" target="_blank">ncoghlan@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class="gmail_quote"><div class="im">On Tue, Nov 20, 2012 at 11:45 PM, Christian Tismer <span dir="ltr"><<a href="mailto:tismer@stackless.com" target="_blank">tismer@stackless.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div>On 20.11.12 12:39, Nick Coghlan wrote:<br>
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<div class="gmail_quote">On Tue, Nov 20, 2012 at 7:06 PM, Kristján
Valur Jónsson <span dir="ltr"><<a href="mailto:kristjan@ccpgames.com" target="_blank">kristjan@ccpgames.com</a>></span>
wrote:<br>
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<p class=""><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">I’m
intrigued. I thought this was merely so that one
could do</span></p>
<p class=""><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">python
–m mypackage.mysubpackage</span></p>
<p class=""><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">Can
you refer me to the rationale and discussion about
this feature?</span></p>
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It was part of a fairly long progression in changes to the
command line execution support :)<br>
<br>
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).<br>
<br>
In the specific case of directory and zipfile execution,
discussion happened on the tracker: <a href="http://bugs.python.org/issue1739468" target="_blank">http://bugs.python.org/issue1739468</a><br>
<br>
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 :(<br>
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Hi Nick,<br>
<br>
thank you very much for this story and the link to the issue
tracker!<br>
A very good move for Python which is really not mentioned enough<br>
to make people more aware of a great feature.<br>
<br>
I think part of this discussion should get a more prominent place<br>
for gems that can be found without knowing what to search. ;-)<br></div></blockquote></div><div><br>Technically, that's the "using" guide: <a href="http://docs.python.org/2/using/cmdline.html#interface-options" target="_blank">http://docs.python.org/2/using/cmdline.html#interface-options</a> (see the explanation of what's executable under the "<script>" tag)<br>
<br>I also wrote up a summary last year on my blog: <a href="http://www.boredomandlaziness.org/2011/03/what-is-python-script.html" target="_blank">http://www.boredomandlaziness.org/2011/03/what-is-python-script.html</a><br>
<br>(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)<br>
<br>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 :)<br> </div><div class="im"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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Is the issue tracker permanent enough to reference it?<br></div></blockquote></div><div><br>I've been referencing that particular issue for years now, so I certainly think so :)<br> <br></div><div class="im"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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Maybe there could be some auxiliary info page with proper keywords<br>
that collects links to relevant discussions like this.<br>
Do we have such a thing already?<br></div></blockquote></div><div><br>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.<br>
</div></div></blockquote><div><br>The wheel projects' own wheel file (a zip file) takes advantage of this feature in its own way:<br><pre>python wheel-0.14.0-py2.py3-none-any.whl/wheel<br></pre>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).<br>
<br><br>This underutilized feature of executing directories with __main__.py is very useful for implementing Python applications instead of just libraries.<br><br>It might be interesting to define a "wheels" format which would be a bunch of unpacked wheel files and a __main__.py like:<br>
<br>__main__.py<br>package1-x86.whl/...<br>package1-armel.whl/...<br>package2-noarch.whl/<br><br>__main__.py would add the appropriate packages to PYTHONPATH based on the architecture, unpack dll's pkg_resources style, and run the program.<br>
<br><br>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.<br><br>Daniel Holth<br></div></div>
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