On Sat, Mar 30, 2013 at 7:07 PM, Brett Cannon <brett@yvrsfo.ca> wrote:
On Mar 30, 2013 3:23 PM, "Daniel Holth" <dholth@gmail.com> wrote:
Python ZIP Application Support -
https://docs.google.com/document/d/1MKXgPzhWD5wIUpoSQX7dxmqgTZVO6l9iZZis8dnr...
PEP: 4XX
Title: Improving Python ZIP Application Support
Author: Daniel Holth <dholth@gmail.com>
Status: Draft
Type: Standards Track
Python-Version: 3.4
Created: 30 March 2013
Post-History: 30 March 2013
Improving Python ZIP Application Support
Python has had the ability to execute directories or ZIP-format archives as scripts since version 2.6. When invoked with a zip file or directory as its first argument the interpreter adds that directory to sys.path and executes the __main__ module. These archives provide a great way to publish software that needs to be distributed as a single file script but is complex enough to need to be written as a collection of modules.
This feature is not as popular as it should be for two reasons: a) users haven’t heard of it because it wasn’t mentioned in earlier versions of Python 2.6 “What’s New” document, and b) Windows users don’t have a file extension (other than .py) to associate with the launcher.
This PEP proposes to fix these problems by re-publicising the feature, defining the .pyz and .pyzw extensions as “Python ZIP applications” and “Windowed Python Zip Applications”, and providing some simple tooling to manage the format.
A New Python ZIP Application Extension
The Python 3.4 installer will associate .pyz and .pyzw “Python ZIP Applications” with itself so they can be executed by the Windows launcher. A .pyz archive is a console application and a .pyzw archive is a windowed application. This indicates whether the console should appear when running the app.
Why not use .zip or .py? Users expect a .zip file would be opened with an archive tool, and users expect .py to be opened with a text editor. Both would be confusing for this use case.
For UNIX users, .pyz applications should be prefixed with a #! line pointing to the correct Python interpreter and an optional explanation.
#!/usr/bin/env python
# This is a Python application stored in a ZIP archive.
... built using pyzaa.
(binary contents of archive)
As background, ZIP archives are defined with a footer containing relative offsets from the end of the file. They remain valid when concatenated to the end of any other file. This feature is completely standard and is how self-extracting ZIP archives and the bdist_wininst installer format work.
Minimal Tooling: The pyzaa Module
This PEP also proposes including a simple application for working with Python ZIP Archives: The Python Zip Application Archiver “pyzaa” (rhymes with “huzzah” or “pizza”). “pyzaa” can archive or extract these files, compile bytecode, and can write the __main__ module if it is not present.
Usage
python -m pyzaa (pack | unpack | compile)
python -m pyzaa pack [-o path/name] [-m module.submodule:callable] [-c] [-w] [-p interpreter] directory:
ZIP the contents of directory as directory.pyz or [-w] directory.pyzw. Adds the executable flag to the archive.
-c compile .pyc files and add them to the archive
-p interpreter include #!interpreter as the first line of the archive
Would `/usr/bin/env python` (or python3 depending on interpreter used to compile) be set otherwise? Or how about the specific python version to prevent possible future-compatibility issues (e.g. specifying python3.3)?
-o path/name archive is written to path/name.pyz[w] instead of dirname. The extension is added if not specified.
-m module.submodule:callable __main__.py is written as “import module.submodule; module.submodule.callable()”
pyzaa pack will warn if the directory contains C extensions or if it doesn’t contain __main__.py.
python -m pyzaa unpack arcname.pyz[w]
The archive is unpacked into a directory [arcname]
Is this truly necessary? If it's a zip file any archiving tool can unzip it. Heck, we can add a CLI to the ziofile module if it doesn't already have one.
It is a convenience so that the contents don't wind up in $PWD, I like the idea of dropping it though. I'll be sure to emphasize that these are completely standard ZIP archives with a new extension. I'm pretty sure zipfile has a CLI. The pack command is a convenience on top of zip & cat. Hope we don't need ignore / MANIFEST.in type features...
python -m pyzaa compile arcname.pyz[w]
The Python files in arcname.pyz[w] are compiled and appended to the ZIP file.
I would suggest allowing multiple versions for compilation (when specified). There should also be a check that people don't specify multiple versions that can't exist on the same directory (e.g 2.6 and 2.7). Otherwise the compileall module's CLI handles this and people can call it with different interpreters as necessary.
If that's easy with compileall then great.
IOW I'm advocating KISS for what the tool does. Since making the zip file is only really tricky bit it should only handle that case. Heck you can make it part of the zipfile module if there is resistance to adding yet another script that python installs (obviously will need a Cheeseshop package for older versions).
Otherwise I like everything else.
Thanks!
-Brett
References
[1] http://bugs.python.org/issue1739468 “Allow interpreter to execute a zip file”
Copyright
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