[AstroPy] [astropy-dev] Coordinates subpackage - request for help

Demitri Muna demitri.muna@gmail....
Fri Nov 16 11:41:56 CST 2012


I would be in favor of using AST as a back end for several reasons.

* There is value to using a single piece of code over reimplementing a new one. From a user's perspective, there is no value in a pure-Python implementation over a C-based one. Those are details they should not be aware of, and our aim here is to make them agree to as high a precision as possible. Work is not duplicated - we have scant resources and a monumental task ahead (astropy).

* The *most important thing to me* is a clean, easy to use API. (Aside from accuracy. :) I see no reason why this has to be sacrificed at all, so while there might be a little pain up front for us to write the glue code, I think that's fine.

* The 12MB size I think is trivial, and if it takes a few more minutes to compile, I think that's fine. I would also advocate hosting/distributing prebuilt binaries. The number of versions needed for the whole Mac universe is small and easy to maintain, the more popular Linii can be made, and anything else should compile. If it doesn't, we push the issue back upstream and not fix it ourselves. David, what are the external dependencies? Can the library be built as a distributable static library?

* I haven't ever used (or seen) pyast, but my knee-jerk reaction is that I don't want any layer at all between the C AST and astropy code.

* Getting lots of features "for free" seems like a huge win, and even if the astropy classes don't expose them yet, it will be far easier to write a good API than to reimplement the functionality.

* I would like to get Erik's thoughts on the question of providing a means to extend transformations. David, are there hooks in AST to do this? I don't know what it would entail.

I think there are issues in making this work, but I think it's a good direction to investigate. If we had infinite resources to work on astropy that might be one thing, but getting a mountain of functionality that will free others to work on other things seems like a win.


Demitri Muna

Center for Cosmology and Particle Physics
New York University


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