[Wheel-builders] pinned-down dependencies for building wheel versus loose dependencies for experimentation

[Philippe Ombredanne]

On Thu, Sep 8, 2016 at 10:23 AM, Philippe Ombredanne
<pombredanne at nexb.com> wrote:
> On Wed, Sep 7, 2016 at 11:00 PM, vitaly numenta
> <vitaly.krugl.numenta at gmail.com> wrote:
>> I would like to structure my project such that when I build a wheel for
>> deployment to PyPi, the wheel uses the pinned-down versions of dependencies,
>> but during development/experimental builds uses the
>> abstract/loosely-versioned dependencies.
>>
>> I want developers to be able to use the abstract dependencies for
>> experimenting with my package against other versions of the dependencies,
>> but installs of my wheel from PyPi need to reference the concrete
>> (pinned-down) dependencies with which my build system actually tested my
>> wheel.
>>
>> Users that install my wheel from PyPi will not (and should not need to) have
>> access to my package's requirements.txt.
>
> Vitaly:
> you cannot treat setup.py as a both a flexible set of version ranges
> and a pinned set at the same time.
> For a detailed explanation please read Donald's post here:
> https://caremad.io/2013/07/setup-vs-requirement/
>
>> However, when building a wheel, I don't see a way to build one that incorporates the pinned-down dependencies from requirements.txt instead of the loosely-versioned requirements from `extras_require`.
>
> The requirements are not used by setup.py and THEY SHOULD NOT, IMHO.
> Use requirements for pinned versions, not setup.py.

In particular if based on your email this is some code you are talking
about I would never do this:
https://github.com/numenta/nupic/blob/d2aad354226bba6b554c706e74e18b3ed4415a0f/setup.py#L84
e.g. I would NEVER source install_requires from a requirements.txt
because this would rob my users and flexibility from any flexibility
in versions.

I find quite unfortunate that there are so many setup.py that do this
and so many snippets and SO posts that recommend this.  **sigh** This
is the source of many problems, like the one you are facing.

-- 
Cordially
Philippe Ombredanne