[Distutils] setup_requires for dev environments

[Chris McDonough]

On 03/16/2015 02:53 PM, Daniel Holth wrote:
> No one should be asked to learn how to extend distutils, and in
> practice no one knows how.
>
> People have been begging for years for working setup_requires, far
> longer than I've been interested in it, and all they want to do is
>
> import fetch_version
> setup(version=fetch_version(), ...)
>
> Then they will eventually notice setup_requires has never worked the
> way most people expect. As a result there are too few setup.py
> abstractions.

FWIW, this particular use case (retrieving the version by importing it 
or a function that returns it after it reads a file or whatever), is 
dodgy.  It's way better that code that needs version info inside the 
package consult pkg_resources or some similar system:

import pkg_resources
version = pkg_resources.get_distribution('mydistro').version

I realize there are other use cases that setup_requires solves, and that 
using pkg_resources can be a performance issue.   I also realize that 
people badly want to be able to "from mypkg import version" or "from 
mypkg import get_version".   But I'd try to come up with a different 
sample use case for driving decision-making because IMO we should 
dissuade them from doing that.  Python packaging should be able to 
provide them this information, they should not need to provide it 
themselves.

- C