On 17 March 2015 at 12:32, Donald Stufft
On Mar 16, 2015, at 7:03 PM, Nick Coghlan
wrote: On 17 Mar 2015 02:33, "Daniel Holth"
wrote: Problem: Users would like to be able to import stuff in setup.py. This could be anything from a version fetcher to a replacement for distutils itself. However, if setup.py is the only place to specify these requirements there's a bit of a chicken and egg problem, unless they have unusually good setuptools knowledge, especially if you want to replace the entire setup() implementation.
Problem: Having easy_install do it is not what people want and misses some important use cases.
Problem: Based on empirical evidence PEP 426 will never be done. Its current purpose is to shut down discussion of pragmatic solutions.
Slight correction here: one of my current aims with PEP 426 is deliberately discouraging the discussion of solutions that only work reliably if everyone switches to a new build system first. That's a) never going to happen; and b) one of the key mistakes the distutils2 folks made that significantly hindered adoption of their work, and I don't want us to repeat it.
My other key aim is to provide a public definition of what I think "good" looks like when it comes to software distribution, so I can more easily assess whether less radical proposals are still moving us closer to that goal.
Making pip (and perhaps easy_install) setup.cfg aware, such that it assumes the use of d2to1 (or a semantically equivalent tool) if setup.cfg is present and hence is able to skip invoking setup.py in relevant cases, sounds like just such a positive incremental step to me, as it increases the number of situations where pip can avoid executing a Turing complete "configuration" file, without impeding the eventual adoption of a more comprehensive solution.
I don't think that needs a PEP - just an RFE against pip to make it d2to1 aware for each use case where it's relevant, like installing setup.py dependencies. (And perhaps a similar RFE against setuptools)
Projects that choose to rely on that new feature will be setting a high minimum installer version for their users, but some projects will be OK with that (especially projects private to a single organisation after upgrading pip on their production systems).
Cheers, Nick.
I don’t think that’s going to work, because if you only make pip aware of it then you break ``python setup.py sdist``, if you make setuptools aware of it then you don’t need pip to be aware of it because we’ll get it for free from setuptools being aware of it.
Huh?
I think the key tests are:
- what happens with old tools
- what happens with new tools
With old tools it needs to not-break.
With new tools it should be better :).
Teaching pip, double-entered setup_requires (.cfg and .py).
old tools keep working
new tools are shiny (pip install -e / vcs then setup's easy_install
call short-circuits doing nothing).
Teaching only setuptools, double-entered
old tools keep working
new tools are not shiny, because pip isn't doing the install
Teaching only setuptools, single entry
old tools break (requirements absent, or you have a versioned dep on
setuptools in setup.py and omg the pain)
new tools are not shiny, same reason
Teaching setuptools and pip, single entry
old tools break - as above
new tools are shiny (because pip either asks setuptools or reads
setup.cfg, whatever)
So I think we must teach pip, and we may teach setuptools.
-Rob
--
Robert Collins