Enable Python bindings

[traversaro]

There is an effort upstream to provide Python bindings. We should package them as well in conda-forge. Given that ign-math is one of the foundation (and also simples) ignition packages, we should pay attention on how we do this so that we can then replicate it in other ignition packages.

In particular, the easiest option is probably to just add python as a dependency (as I did for example in https://github.com/conda-forge/idyntree-feedstock/blob/0c58bf41cde4e7a50c9b97279b8e206b531b1ac8/recipe/meta.yaml) but in that case the lib** name would not have a lot of sense, and that may add a unwanted dependency on downstream C++ users. A more complex option would be to have split outpus between the C++ library and the Python bindings, but to be honest I never was able to fully grasped how to do that in the best way.

[traversaro]

Related discussion in staged-recipes: conda-forge/staged-recipes#18234 (comment) .

[traversaro]

I tried again to check some recipes that generate split packages for C++ and the related Python bindings, such as:

• https://github.com/conda-forge/opencv-feedstock/blob/97f30ba40f9342ab979acef8206830851d0b5df1/recipe/meta.yaml
• https://github.com/conda-forge/libode-feedstock/blob/cc06c551966df77cb0a9c283c3fe5797d78ab981/recipe/meta.yaml

However, the logic is quite complex and I do not see enough benefit in having split packages that justify the additional mantainance effort. So, for now I will just enable the python dependency in the ignition packages that have Python bindings, then anyone interested is welcome to work in renaming the ignition library to remove the lib prefix or to produce split packages.

[traversaro]

work in renaming the ignition library to remove the lib prefix

For that probably we can wait for the Ignition -> Gazebo renaming, whenever we rename the packages to gazebo- we can drop the lib prefix.

[traversaro]

Fixed by #25 .