[Distutils] tourist here, with a dumb RTFM question

[Jason R. Coombs]

From: Distutils-SIG [mailto:distutils-sig-bounces+jaraco=jaraco.com at python.org] On Behalf Of Marcus Smith
Sent: Thursday, 06 March, 2014 16:16
To: DistUtils mailing list
Subject: Re: [Distutils] tourist here, with a dumb RTFM question



On Thu, Mar 6, 2014 at 10:37 AM, Michael Bayer <mike_mp at zzzcomputing.com<mailto:mike_mp at zzzcomputing.com>> wrote:

On Mar 6, 2014, at 1:07 PM, Daniel Holth <dholth at gmail.com<mailto:dholth at gmail.com>> wrote:

> pje said:
>
> The "Feature()" facility was never completely implemented or
> supported, and even if it were, it should be deprecated now, as it
> will not be compatible with the coming packaging systems based on PEP
> 426. If you need separate features, use separate distributions and
> "extras" instead.
wait, ok this is that thing.  "separate distributions" means....


SQLAlchemy-0.9.3-nocext.tar.gz
SQLAlchemy-0.9.3-cext.tar.gz

I'm new to understanding setuptools "Feature" myself, so don't crank too much, if I get anything wrong.

afaik, it means something like:

SQLAlchemy-X.Y.tar.gz
SQLAlchemy-cext-X.Y.tar.gz

i.e. isolating the feature into a separate project.

and then instead of having the handy  "--with-cext" option,  it has to be  "pip install SQLAlchemy[SQLAlchemy-cext]

PJ, Jason: can you clarify what the alternative is supposed to look like?

I'm new to understanding Features as well, but based on PJ's post, I would agree with Marcus here. This is how I interpreted the use of extras to supersede Features. I see a lot of advantages to this approach over build-time selection. Because it decouples the main project from the C-extension speedups, it gives the installer control over what behavior is present. It also gives deployment tools visibility over what capability is present (with features, it's harder to tell if the C-extension speedups are present; with extras, one can query pkg_resources).

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