On May 1, 2008, at 4:51 PM, email@example.com wrote:
I'm not on distutils-sig, but this is probably of little interest to python-dev. Please Cc: me if you think my continued input would be useful to this discussion.
On 08:25 pm, firstname.lastname@example.org wrote:
almost always in the phrase, "please do not use distutils to do a system install of Twisted, use the specific package for your platform".
This is a tangent, but why do you give that advice? I typically give people the opposite advice on how to install Twisted.
The #1 reason:
- distutils does not provide an uninstaller.
This means that a user who has installed a Python library - but especially a package like Twisted, which uses a shared namespace with other libraries that use it, twisted.plugins - can't easily get rid of it. I only ever use 'setup.py' in conjunction with '-- prefix'; in my opinion, the *default* behavior of distutils should be "--prefix ~/.local".
Definitely not the only reason, though. Even if distutils had a great uninstaller, I still probably wouldn't recommend it...
- distutils will interfere with the system package manager,
potentially breaking it, by writing files to locations reserved for the system package manager (/usr, et. al.)
- distutils won't uninstall a system-installed version of the
package first, so if you use e.g. --force to overwrite your system files, you may end up with leftover system packaged (incompatible, earlier-version) plugins or modules which break your distutils install
- running arbitrary, non-vendor-supported code as root as a matter
of habit is, in my humble opinion, bad; distutils requires you to run as root for the default behavior to work. the system package manager typically requires root permission too, but at least it's the sort of thing which has been audited.
- not only can you not reverse the process, there's no way to *tell*
if distutils has crapped all over your system installation of a particular package
- setuptools causes seemingly random breakages (in packages which
support it), and I don't want to deal with bug reports from users related to packaging; packagers are capable of dealing with setuptools' interactions with the platform and creating a nice, neat bundle that works as expected.
- when you say "distutils", what do you mean? running 'setup.py'
from some random revision of trunk? doing 'sdist' from trunk, then install? Using operating-system packages at least suggests that you're using a release, or if not an actual release, you've gone through something approximating the actual release/build process that we suggest for users.
- if the user is installing for development anyway, and not for
deployment, then why bother doing any installation step at all? It's probably better to just drop an SVN checkout on PYTHONPATH somewhere.
- why bother having installers prepared for particular systems, if
they are not the preferred way of doing things? If and when distutils is ready to be the thing I will suggest to users, I imagine that we'll stop having operating system packages. (Of course, that begs the question why distutils would have commands like "bdist_wininst" - it's difficult to beat the native packages for convenience.)
These are very good arguments for not using distutils to install packages into a system Python.
I'll note that I *never* use distutils that way. :) (I may be in the minority though.)
-- Jim Fulton Zope Corporation