[Distutils] PEP: Improving Python ZIP Application Support

[PJ Eby]

On Sun, Mar 31, 2013 at 1:09 PM, Philippe Ombredanne
<pombredanne at nexb.com> wrote:
> On Sat, Mar 30, 2013 at 8:22 PM, Daniel Holth <dholth at gmail.com> wrote:
>> Python ZIP Application Support -
>> https://docs.google.com/document/d/1MKXgPzhWD5wIUpoSQX7dxmqgTZVO6l9iZZis8dnri78/edit?usp=sharing
>> PEP: 4XX
>> Title: Improving Python ZIP Application Support
> So I guess that this already-available-yet-hidden-or-little-known
> feature we had since Python 2.6 will be getting a little light.
>
> Let me ask a few silly questions:
>
> Does this means that any zip with a __main__.py is de-facto already executable?
Yes.

> What about a wheel with a __main__ ? or an egg?
Yes.

> Or a source archive where the __main__ calls setup.py install or
> buildout bootstrap?

Yep.


> Is this something to promote?

Why not?

> How is this overlapping with other packaging approaches? or possibly
> replacing them all?

It helps make things easier to install that are themselves installation tools.

By the way, after some experimenting this morning, I have figured out
how to make this work with Python 2.3 and up in a fairly simple way.
It turns out that if you stick a .py file on the front of a zipfile,
and you end it with a '#' and a few special characters, then when you
run the zipfile with 2.6+, the __main__ is executed, but for 2.3-2.5,
the .py  header is executed.  If this header does sys.path.insert(0,
__file__), it then can import things from the zipfile.  So, with an
appropriate header, you can make a one-size-fits-all executable
zipfile.

In practice, there are a couple of wrinkles.  The magic terminator
string, at least for the Windows and Linux boxes I've tested so far,
is '\n#\x1a\n\x00\n'.  But there are more platforms and builds I
*haven't* tested on than those I have.