Add numpy as setup requirement

[kylebarron]

We got a downstream bug report of rio-color's install failing because the user didn't have numpy installed when he tried to install rio-color, so the headers couldn't be found.

This is a bit of a chicken-and-egg issue, because the numpy headers are needed to build, but you can't find them before installing numpy. This PR uses a technique I learned from pybind11 (though I can't find now exactly where in the documentation it was referenced), which uses a class to postpone finding numpy's headers until numpy is installed.

Tested locally (using conda just to create a virtual env):

Setup:

> conda create -n minimal-test -c conda-forge python -y
> source activate minimal-test

Before:

> python setup.py bdist_wheel
Numpy and its headers are required to run setup(). Exiting.

After, creating the wheel works.

[kylebarron]

It looks like you could use this same technique in rasterio
https://github.com/mapbox/rasterio/blob/1d43837d1591c7bc3cc87c97e45f153063103d57/setup.py#L88-L92

[kylebarron]

@vincentsarago suggested a generator instead of a class, and it seems to work fine as well

[vincentsarago]

Maybe the class is overpriced!
a simple function should be enough

def get_numpy_include():
    import numpy
    yield numpy.get_include()

and the in the setup() do

    include_dirs=[get_numpy_include()],
    setup_requires=["numpy"],

🤷‍♂️

[vincentsarago]

:homer:

[kylebarron]

[sgillies]

We don't want to make rasterio more like this PR. Instead we want to make this project more like rasterio. See #64 😄

setup_requires hasn't ever really worked. The modern approach is to give the project a file like https://github.com/mapbox/rio-color/blob/master/pyproject.toml defining its build requirements. The build system will fetch numpy before building and then the code at https://github.com/mapbox/rio-color/blob/master/setup.py#L14-L21 will (in theory) never exit.

I'm happy to discuss this more but we're not going to merge this PR. The big blocker right now is #65 and my lack of time to review #66. However, I can see the light at the end of the tunnel.

[sgillies]

@vincentsarago @kylebarron since you're writing packages that depend on rio-color and have conda users, it could be good to add rio-color to conda-forge. I think they have good instructions and examples, shouldn't be too hard.

[kylebarron]

I see... pip install git+https://github.com/mapbox/rio-color does work in my minimal environment, fetching Numpy first. I didn't check for new unreleased commits.

I personally get very frustrated dealing with Conda packaging. Someone made a Conda release of rio-tiler v1, but since then we've added more dependencies, so once rio-tiler v2 is released it'll take some time to become a conda package. Presumably at some point someone will make a rio-color dist on Conda.

[vincentsarago]

@sgillies I'm not sure to fully understand the pyproject.toml but does this mean the issue has been resolved in master but not in pypi? again thanks for your time 🙏

[sgillies]

Correct @vincentsarago . 1.0.0 did not specify build dependencies, but 1.0.1 will. The thing that's blocking me from releasing 1.0.1 is lack of working wheel building infra. If I made a source-only 1.0.1 release, this tracker would fill up with "I can't install 1.0.1" issues.

[vincentsarago]

🙏 thanks @sgillies

[vincentsarago]

I'll just ping @jacquestardie so he finds some time for you then!

[sgillies]

@vincentsarago ping him hourly!