[Distutils] Are egg files needed when building/installing via --root?
zooko at zooko.com
Mon Dec 1 04:17:14 CET 2008
On Nov 30, 2008, at 17:39 PM, Josselin Mouette wrote:
> When stripping .egg-info files, you run into problems with useless
> code that checks for dependencies (while the packaging system
> already checks for them), so you have to strip such code as well.
Let's put it like this: as the author of an application and some
libraries written in Python, I would like it if my code could run on
$operating_system_distribution even before someone has gotten around
to packaging it for $operating_system_distribution. Therefore, I
need a way to tell whether some dependency is already installed. I
could write a giant switch statement for all known package management
if platform.dist() == 'debian':
elif platform.dist() == 'redhat':
elif platform.system() == 'windows':
# probe registry ???
My code currently runs on nine operating systems and I hope to
support a lot more before I'm through, so this switch statement would
be a significant undertaking to support my users on various platforms.
Fortunately, pkg_resources does this for me in a generic, cross-
platform way so that my workload is substantially reduced:
pkg_resources.require('my_dependency >= 1.0')
Note, this didn't use to work so well on some Linux distributions
back in the bad old days when they removed .egg-info files, but
nowadays it works very well on all of the aforementioned nine
operating system distributions that I am aware of.
Now, you as a Debian developer may feel that you would have developed
my application differently than me, such as perhaps step 1: make the
code run on $operating_system_distribution even before it has been
packaged for $operating_system_distribution, or you may not, but
either way I truly appreciate that nowadays you preserve the .egg-
info files so that I have the option of doing it this way.
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