[Distutils] [final version?] PEP 513 - A Platform Tag for Portable Linux Built Distributions

[Matthias Klose]

On 02.02.2016 02:35, Glyph Lefkowitz wrote:
>
>> On Feb 1, 2016, at 3:37 PM, Matthias Klose <doko at ubuntu.com> wrote:
>>
>> On 30.01.2016 00:29, Nathaniel Smith wrote:
>>> Hi all,
>>>
>>> I think this is ready for pronouncement now -- thanks to everyone for
>>> all their feedback over the last few weeks!
>>
>> I don't think so.  I am biased because I'm the maintainer for Python in Debian/Ubuntu.  So I would like to have some feedback from maintainers of Python in other Linux distributions (Nick, no, you're not one of these).
>
> Possibly, but it would be very helpful for such maintainers to limit their critique to "in what scenarios will this fail for users" and not have the whole peanut gallery chiming in with "well on _my_ platform we would have done it _this_ way".
>
> I respect what you've done for Debian and Ubuntu, Matthias, and I use the heck out of that work, but honestly this whole message just comes across as sour grapes that someone didn't pick a super-old Debian instead of a super-old Red Hat.  I don't think it's promoting any progress.

You may call this sour grapes, but in the light of people installing
these wheels to replace/upgrade system installed eggs, it becomes an issue. It's 
fine to use such wheels in a virtual environment, however people tell users to 
use these wheels to replace system installed packages, distros will have a 
problem identifying issues.

There is a substantial amount of extensions built using C++; I didn't check how 
many of these in c++0x/c++11 mode.  Until GCC 5, the c++11 ABI wasn't stable, 
and upstream never promised forward compatibility, something that even distros 
have to care about (usually by rebuilding packages before a release).  So if you 
want a lowest common denominator, then maybe limit or recommend the use of c++98 
only.

>> The proposal just takes some environment and declares that as a standard.  So everybody wanting to supply these wheels basically has to use this environment.
>
> There's already been lots of discussion about how this environment is a lowest common denominator.  Many other similar environments could _also_ be lowest common denominator.

sure, but then please call it what it is. centos5 or somelinux1.

> In the future, more specific and featureful distro tags sound like a good idea.  But could we please stop making the default position on distutils-sig "this doesn't cater to my one specific environment in the most optimal possible way, so let's give up on progress entirely"?  This is a good proposal that addresses environment portability and gives Python a substantially better build-artifact story than it currently has, in the environment most desperately needing one (server-side linux).  Could it be better?  Of course.  It could be lots better.  There are lots of use-cases for dynamically linked wheels and fancy new platform library features in newer linuxes.  But that can all come later, and none of it needs to have an impact on this specific proposal, right now.

I'm unsure how more specific and featureful distro tags will help, unless you 
start building more than one binary version of a wheel.  From a distro point of 
view I only can discourage using such wheels outside a virtual environment, and 
I would like to see a possibility to easily identify such wheels, something like 
loading a binary kernel module is tainting the kernel. This way distros can 
point users to the provider of such wheels.

This is not a "this doesn't cater to my one specific environment" position. Of 
course you probably get less push back from other distributions closer to the 
specific environment specified in the pep.  But please acknowledge that there 
might be issues that you and me don't yet even see, and provide a possibility to 
identify such issues.

At least Debian/Ubuntu took a long ride to avoid "accidental" interaction with 
local Python installations and local installations into the system installed 
Python.  For me this PEP feels like a step back, promising too much (manylinux), 
not pointing out possible issues, and giving no help in identifying possible 
issues with these wheels.

Matthias