Dear Tarek Ziadé and fellowship of the packaging:
Please pay attention to this issue. If we can extend our build
processes in a modular, re-usable, and testable way then this could
contribute to the success of distutils/setuptools/Distribute.
In particular, I want Nevow to be automatically installable as a
dependency (using, for now, setuptools, but presumably the same will
apply to Distribute), and one of the issues is still outstanding and
Glyph refuses to accept my patch which fixes it because the fix isn't
testable.
http://divmod.org/trac/ticket/2699
I want Distribute-compatible build extensions to be accepted by
Glyph. This requires that they be testable. Please help me
understand how to write build extensions which are testable.
Regards,
Zooko
On Sunday,2009-08-16, at 14:16 , Zooko Wilcox-O'Hearn wrote:
Folks:
I have a recurring problem with distutils/setuptools/Distribute,
which is that I don't know how to extend the functionality of
setup.py and make the new functionality be testable and modular.
Here's one specific example that I currently have a lot of
experience with: I'd like to generate a version number from
revision control history. Don't get hung up on the desired
functionality though -- if you think that generating version
numbers is best done a different way, or if you don't care about
generating version numbers, then please just mentally insert some
other extension of your build functionality that you do care about.
I'm familiar with three different ways to implement an extension
like this.
The first is what Nevow does [1], which is to write in setup.py
"from nevow import __version__". Well, this works in the case that
setup.py is being executed as the command-line script in a fresh,
empty Python interpreter, but it fails in the case that the Python
interpreter has already been running for a while, has already
imported nevow (a *different* nevow from a different location on
the local filesystem), and is now importing *this* nevow's setup
module in order to build this nevow. This happens with setuptools
and py2exe. Distribute v0.6 includes a patch [2] to fix this, but
I'm not sure the patch is right (it involves 'for m in
various_modules: del sys.modules[m]' and it doesn't seem to fix all
cases). PJE says "Thou shalt not import yourself when trying to
build yourself" [3]. Glyph says "Then how do I test this
code?" [4]. I say "Ugh, I don't know. Let's look at the other two
ways to do it."
The second is what I do in some of my packages such as pycryptopp
[5]. Just take that functionality that you want to add to all of
your packages and cut and paste the code into each of your
setup.py's, then edit it a little to reflect the correct name of
the current package. This sucks because you're cutting and pasting
code, because your setup.py gets bigger and hairier the more
functionality your build system has, and because, again, you can't
test it.
The third is what I do in Tahoe-LAFS [6]. I moved the
functionality in question into a separate Python package, in this
case named "darcsver" [7], and used setuptools's plugin system to
add a command named "darcsver" which initializes the
distribution.metadata.version attribute correctly. Then I had to
add a bunch of aliases to my setup.cfg [8] saying "If you're going
to build, first darcsver, and if you're going to install, first
darcsver, and ...". This sort of works, except that yesterday my
programming partner Brian Warner informed me [9] that he expected
the "python ./setup.py --version" command-line to output the
version number. Argh! There is no way to configure in my
setup.cfg "If you're going to --version, first darcsver.".
So it appears to me that none of these techniques are both modular/
testable and compatible with distutils/setuptools/Distribute. What
are we to do?
Regards,
Zooko
[1] http://www.divmod.org/trac/browser/trunk/Nevow/setup.py?rev=17531
[2] http://bugs.python.org/setuptools/issue20
[3] http://bugs.python.org/setuptools/msg139
[4] http://www.divmod.org/trac/ticket/2699#comment:20
[5] http://allmydata.org/trac/pycryptopp/browser/setup.py?rev=661#L181
[6] http://allmydata.org/trac/tahoe/browser/setup.py?rev=4036#L97
[7] http://allmydata.org/trac/darcsver
[8] http://allmydata.org/trac/tahoe/browser/setup.cfg?rev=3996#L46
[9] http://allmydata.org/trac/darcsver/ticket/6
_______________________________________________
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_______________________________________________
Distutils-SIG maillist - [email protected]
http://mail.python.org/mailman/listinfo/distutils-sig
