Mailman 3 June 2011 - Distutils-SIG

3.3 / packaging - support for Windows installation locations
by Vinay Sajip June 19, 2011

June 19, 2011

While packaging's support for path-based installation seems reasonably comprehensive, on recent Windows versions, installation locations aren't always simply based on fixed or declaratively specifiable locations. For example, say that some data needs to be installed in a user's "Documents" folder under Windows 7. You might assume that this would be e.g. "C:\Users\Vinay\Documents", but in fact that might not be the correct location. To do it correctly for all scenarios involves jumping through some hoops: from ctypes import windll, Structure, byref, w_char_p # and other stuff besides class GUID(Structure): # define a GUID structure in terms of ctypes longs, shorts etc. Documents_FolderID = GUID(...) # using constants from Windows KnownFolders.h path = w_char_p() # to hold the resulting path windll.shell32.SHGetKnownFolderPath(byref(Documents_FolderID), ..., byref(path), ...) and then use path.value as the location of the Documents folder. What's the best way of handling these sorts of situations with Python 3.3 packaging? Regards, Vinay Sajip

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DRAFT PEP 396 - module version number
by Barry Warsaw June 9, 2011

June 9, 2011

Hi distutilizers! At Pycon, I signed up to write an informational PEP on module version numbers. There have been some email discussion since then, and while I haven't completely worked my way through all those messages yet, I think I have covered the important top-level issues. I'm posting my current draft (as yet uncommitted to the new hg repository) here before taking it to python-dev. I'd love to get your feedback about any aspect of the PEP, but especially on deriving module version numbers from setup.cfg files, and on including them in metadata at build time (as opposed to installation time). Also, I'd appreciate any corrections based on my misunderstanding of distutils2/packaging and the relevant PEPs. Current draft attached below. Remember, this is an informational PEP, so its purpose is to codify best practices. Module authors will continue to have the freedom to do whatever they want. Cheers, -Barry PEP: 396 Title: Module Version Numbers Version: $Revision: 65628 $ Last-Modified: $Date: 2008-08-10 09:59:20 -0400 (Sun, 10 Aug 2008) $ Author: Barry Warsaw <barry(a)python.org> Status: Draft Type: Informational Content-Type: text/x-rst Created: 2011-03-16 Post-History: Abstract ======== Given that it is useful and common to specify version numbers for Python modules, and given that different ways of doing this have grown organically within the Python community, it is useful to establish standard conventions for module authors to adhere to and reference. This informational PEP describes best practices for Python module authors who want to define the version number of their Python module. Conformance with this PEP is optional, however other Python tools (such as `distutils2` [1]_) may be adapted to use the conventions defined here. User Stories ============ Alice is writing a new module, called ``alice.py``, which she wants to share with other Python developers. ``alice.py`` is a simple module and lives in one file. Alice wants to specify a version number so that her users can tell which version they are using. Because her module lives entirely in one file, she wants to add the version number to that file. Bob has written a module called ``bob.py`` which he has shared with many users. ``bob.py`` contains a version number for the convenience of his users. Bob learns about the Cheeseshop [2]_, and adds some simple packaging using classic distutils so that he can upload *The Bob Package* to the Cheeseshop. Because ``bob.py`` already specifies a version number which his users can access programmatically, he wants the same API to continue to work even though his users now get it from the Cheeseshop. Carole maintains several namespace packages, each of which are independently developed and distributed. In order for her users to properly specify dependencies on the right versions of her packages, she specifies the version numbers in the namespace package's ``setup.py`` file. Because Carol wants to have to update one version number per package, she specifies the version number in her module and has the ``setup.py`` extract the module version number at *sdist* tarball build time. David maintains a package in the standard library, and also produces standalone versions for other versions of Python. The standard library copy defines the version number in the module, and this same version number is used for the standalone distributions as well. Rationale ========= Python modules, both in the standard library and available from third parties, have long included version numbers. There are established de-facto standards for describing version numbers, and many ad-hoc ways have grown organically over the years. Often, version numbers can be retrieved from a module programmatically, by importing the module and inspecting an attribute. Classic Python distutils ``setup()`` functions [3]_ describe a ``version`` argument where the package's version number can be specified. PEP 8 [4]_ describes the use of a module attribute called ``__version__`` for recording "Subversion, CVS, or RCS" version strings using keyword expansion. In the PEP author's own email archives, the earliest example of the use of an ``__version__`` module attribute by independent module developers dates back to 1995. Another example of version information is the sqlite3 [5]_ library with its ``sqlite_version_info``, ``version``, and ``version_info`` attributes. It may not be immediately obvious which attribute contains a version number for the module, and which contains a version number for the underlying SQLite3 library. This informational PEP codifies established practice, and recommends standard ways of describing module version numbers, along with some use cases for when -- and when *not* -- to include them. Its adoption is purely voluntary, but other tools in the Python universe may support the standards defined herein. Specification ============= #. In general, modules in the standard library SHOULD NOT have version numbers. They implicitly carry the version number of the Python release they are included in. #. On a case-by-case basis, standard library modules which are also distributed as standalone packages for other Python versions MAY include a module version number when included in the standard library, and SHOULD include a version number when packaged separately. #. When a module includes a version number, it SHOULD be available in the ``__version__`` attribute on that module. #. For modules which are also packages, the top level module namespace SHOULD include the ``__version__`` attribute. #. For modules which live inside a namespace package, the sub-package name SHOULD include the ``__version__`` attribute. The namespace module itself SHOULD NOT include its own ``__version__`` attribute. #. The ``__version__`` attribute's value SHOULD be a simple string. #. Module version numbers SHOULD conform to the normalized version format specified in PEP 386 [6]_. #. Module version numbers SHOULD NOT contain version control system supplied revision numbers, or any other semantically different version numbers (e.g. underlying library version number). #. Wherever a ``__version__`` attribute exists, a module MAY also include a ``__version_info__`` attribute, containing a tuple representation of the module version number, for easy comparisons. #. ``__version_info__`` SHOULD be of the format returned by PEP 386's ``parse_version()`` function. #. The ``version`` attribute in a classic distutils ``setup.py`` file, or the ``Version`` metadata field in a PEP 345 [7]_ SHOULD be derived from the ``__version__`` field, or vice versa. Examples ======== Retrieving the version number from a third party package:: >>> import bzrlib >>> bzrlib.__version__ '2.3.0' Retrieving the version number from a standard library package that is also distributed as a standalone module:: >>> import email >>> email.__version__ '5.1.0' Version numbers for namespace packages:: >>> import flufl.i18n >>> import flufl.enum >>> import flufl.lock >>> print flufl.i18n.__version__ 1.0.4 >>> print flufl.enum.__version__ 3.1 >>> print flufl.lock.__version__ 2.1 >>> import flufl >>> flufl.__version__ Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: 'module' object has no attribute '__version__' >>> Deriving ======== Module version numbers can appear in at least two places, and sometimes more. For example, in accordance with this PEP, they are available programmatically on the module's ``__version__`` attribute. They also need to be specified in either the classic distutils ``setup()`` function, as the ``version`` attribute in a ``setup.py``, or in the distutils2 ``setup.cfg`` file's ``version`` keyword, and they need to get into the PEP 345 package metadata, preferably at *sdist* package build-time. It's also desirable for module authors to only have to specify the version number once, and have all the other uses derive from this single definition. While there are any number of ways this could be done, this section describes one possible approach, for each scenario. Let's say Elle adds this attribute to her module, ``elle.py``:: __version__ = '3.1.1' Classic distutils ----------------- In classic distutils, the simplest way to add this version to the ``setup()`` function in ``setup.py`` is to do something like this:: from elle import __version__ setup(name='elle', version=__version__) In the PEP author's experience however, this can fail in some cases, such as when the module uses automatic Python 3 conversion via the ``2to3`` program. In that case, it's not much more difficult to write a little code to parse the ``__version__`` from the file rather than importing it:: import re DEFAULT_VERSION_RE = re.compile(r'(?P<version>\d+\.\d(?:\.\d+)?)') def get_version(filename, pattern=None): if pattern is None: cre = DEFAULT_VERSION_RE else: cre = re.compile(pattern) with open(filename) as fp: for line in fp: if line.startswith('__version__'): mo = cre.search(line) assert mo, 'No valid __version__ string found' return mo.group('version') raise AssertionError('No __version__ assignment found') setup(name='elle', version=get_version('elle.py')) Distutils2 ---------- Because the distutils2 style ``setup.cfg`` is declarative, we can't run any code to extract the ``__version__`` attribute, either via import or via parsing. This PEP suggests a special key be allowed for the ``version`` field in a ``setup.cfg`` file to indicate "get the version from this file". Something like this might work:: [metadata] version: parse:elle.py where ``parse`` means to use a parsing method similar to the above, on the file named after the colon. The exact recipe for doing this will be discussed in the appropriate distutils2 development forum. An alternative is to only define the version number in setup.cfg and use the ``pkgutil`` module [8]_ to make it available programmatically. E.g. in ``elle.py``:: from distutils2._backport import pkgutil __version__ = pkgutil.get_distribution('elle').metadata['version'] Static egg info =============== For distutils2, it is highly desirable to place the version information into the egg metadata at build-time rather than install-time. This way, the metadata will be available for introspection even when the code is not installed. For example, a package's metadata can be made available via a simple HTTP GET operation on a URL within the package's presence on the Cheeseshop. References ========== .. [1] Distutils2 documentation (http://distutils2.notmyidea.org/) .. [2] The Cheeseshop (Python Package Index) (http://pypi.python.org) .. [3] http://docs.python.org/distutils/setupscript.html .. [4] PEP 8, Style Guide for Python Code (http://www.python.org/dev/peps/pep-0008) .. [5] sqlite3 module documentation (http://docs.python.org/library/sqlite3.html) .. [6] PEP 386, Changing the version comparison module in Distutils (http://www.python.org/dev/peps/pep-0386/) .. [7] PEP 345, Metadata for Python Software Packages 1.2 (http://www.python.org/dev/peps/pep-0345/#version) .. [8] pkgutil - Package utilities (http://distutils2.notmyidea.org/library/pkgutil.html) Copyright ========= This document has been placed in the public domain. .. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 coding: utf-8 End:

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[PEP376] RECORD line separator
by Atsushi Odagiri June 9, 2011

June 9, 2011

Hi I read pep276, and I have a question. This PEP says that line separator of RECORD file is `os.separator`. and 'bdist-*' command will also create RECORD file. Does it even work with the package which doesn't depend on the OS like bdist_egg ? I think that file format should not depend on os environment and good choice is CRLF. It's standard line separator as used in email headers. by aodag -- /* Atsushi Odagiri http://blog.aodag.jp mailto:aodagx@gmail.com */

2 1

does easy_install.py need to guess the site-packages path?
by James June 8, 2011

June 8, 2011

As an example I'm looking at setuptools-0.6c11-py2.7.egg, can someone tell me why setuptools/command/east_install.py in get_site_dirs() does its own computation of where site-packages is? As of 2.7 there are already 4 separate places in the python where this path is computed. Maybe I'm missing something but I don't see why an egg would have an opinion on this matter. Regards, - James

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why does easy_install set +x on all .py files?
by Erik Bray June 7, 2011

June 7, 2011

Hi all, I've used setuptools for a long time, and yet I've only just noticed this behavior. It came up because I wanted nose to run some installed tests, and it was mysterious as to why it wasn't finding them. Debug output from nose revealed the answer: it was skipping searching those modules because they're exectuable. That's fine, because I can just add --exe to nose. But I was wondering why it is that easy_install sets 0755 on all files? Why not preserve the existing executable bit set on the file? Thanks, Erik

1 0

[buildout] [Errno 104] Connection reset by peer
by Anton Panasenko June 1, 2011

June 1, 2011

Hi guys, Who knows how to fix the problem: Download error: [Errno 104] Connection reset by peer -- Some packages may not be found!

2 1

Distribute 0.6.17
by Tarek Ziadé June 1, 2011

June 1, 2011

Hello I've pushed 0.6.17, which fixes the Python 3.2.1 compat' and a few bugs. Thanks to the people involved in this release. If you have any issue with this release, or want to see a particular problem fixed in the next one, let me know Cheers Tarek -- Tarek Ziadé | http://ziade.org

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