python - Questions about Setuptools and alternatives

Question

I've seen a good bit of setuptools bashing on the internets lately. Most recently, I read James Bennett's On packaging post on why no one should be using setuptools. From my time in #python on Freenode, I know that there are a few souls there who absolutely detest it. I would count myself among them, but I do actually use it.

I've used setuptools for enough projects to be aware of its deficiencies, and I would prefer something better. I don't particularly like the egg format and how it's deployed. With all of setuptools' problems, I haven't found a better alternative.

My understanding of tools like pip is that it's meant to be an easy_install replacement (not setuptools). In fact, pip uses some setuptools components, right?

Most of my packages make use of a setuptools-aware setup.py, which declares all of the dependencies. When they're ready, I'll build an sdist, bdist, and bdist_egg, and upload them to pypi.

If I wanted to switch to using pip, what kind of changes would I need to make to rid myself of easy_install dependencies? Where are the dependencies declared? I'm guessing that I would need to get away from using the egg format, and provide just source distributions. If so, how do i generate the egg-info directories? or do I even need to?

How would this change my usage of virtualenv? Doesn't virtualenv use easy_install to manage the environments?

How would this change my usage of the setuptools provided "develop" command? Should I not use that? What's the alternative?

I'm basically trying to get a picture of what my development workflow will look like.

Before anyone suggests it, I'm not looking for an OS-dependent solution. I'm mainly concerned with debian linux, but deb packages are not an option, for the reasons Ian Bicking outlines here.

Answer 1

pip uses Setuptools, and doesn't require any changes to packages. It actually installs packages with Setuptools, using:

python -c 'import setuptools; __file__="setup.py"; execfile(__file__)' 
    install 
    --single-version-externally-managed

Because it uses that option (--single-version-externally-managed) it doesn't ever install eggs as zip files, doesn't support multiple simultaneously installed versions of software, and the packages are installed flat (like python setup.py install works if you use only distutils). Egg metadata is still installed. pip also, like easy_install, downloads and installs all the requirements of a package.

In addition you can also use a requirements file to add other packages that should be installed in a batch, and to make version requirements more exact (without putting those exact requirements in your setup.py files). But if you don't make requirements files then you'd use it just like easy_install.

For your install_requires I don't recommend any changes, unless you have been trying to create very exact requirements there that are known to be good. I think there's a limit to how exact you can usefully be in setup.py files about versions, because you can't really know what the future compatibility of new libraries will be like, and I don't recommend you try to predict this. Requirement files are an alternate place to lay out conservative version requirements.

You can still use python setup.py develop, and in fact if you do pip install -e svn+http://mysite/svn/Project/trunk#egg=Project it will check that out (into src/project) and run setup.py develop on it. So that workflow isn't any different really.

If you run pip verbosely (like pip install -vv) you'll see a lot of the commands that are run, and you'll probably recognize most of them.