Re: [matplotlib-devel] Experiments in removing/replacing PyCXX

[Michiel de H. <mjl...@ya...>]

In my experience, Benjamin is right that the C code is rarely touched. This is even more true for the Python/C glue code, at least from my experience with the Mac OS X backend. Since the Python/C glue code is modified only very rarely, there may not be a  need for regenerating the Python/C glue code by developers or users from a Cython source code.

In addition, it is much easier to maintain the Python/C glue code than to write it from scratch. Once you have the Python/C glue code, it's relatively straightforward to modify it by looking at the existing Python/C glue code.

This argues against making the Cython source code a part of the matplotlib codebase.

At the same time, to minimize errors, we could use Cython to create the initial Python/C glue code, and then add the generated code to the matplotlib codebase. Then neither users nor developers have to install Cython, we don't have to worry about inconsistencies (if any) between different Cython versions, we don't have to worry about keeping the Cython source code and the generated code in sync, and we will still get a high-quality Cython-generated Python/C glue code.

By the way, how many modules in matplotlib make use of CXX, and would have to be converted?

Best,
-Michiel.

--- On Fri, 11/30/12, Benjamin Root <ben...@ou...> wrote:

From: Benjamin Root <ben...@ou...>
Subject: Re: [matplotlib-devel] Experiments in removing/replacing PyCXX
To: "Nathaniel Smith" <nj...@po...>
Cc: "Michiel de Hoon" <mjl...@ya...>, "mat...@li..." <mat...@li...>, "Chris Barker - NOAA Federal" <chr...@no...>
Date: Friday, November 30, 2012, 8:32 PM



On Fri, Nov 30, 2012 at 6:44 PM, Nathaniel Smith <nj...@po...> wrote:


On Fri, Nov 30, 2012 at 11:40 PM, Michiel de Hoon <mjl...@ya...> wrote:

> One package (Pysam) that I use a lot relies on Cython, and requires users to install Cython before they can install Pysam itself. With Cython, is that always the case? Will all users need to install Cython? Or is it sufficient if only matplotlib developers install Cython?





You can set things up so that end-users don't have to install cython.

You just convert the .pyx files to regular .c files before

distributing your package. Numpy itself uses cython, but end-users

don't notice or care. (It's something more of a hassle for developers

to do things this way, and cython is very easy to install, so I don't

know if it's worth it. But it's certainly possible.)



Since when has numpy used Cython?  I specifically remember a rather involved discussion thread on numpy-discussion about the pros-and-cons of including cython.  Now, SciPy on the other hand, does utilize Cython in some spots IIRC, but does it in a way that it isn't even required for the developers to have cython installed to build from source.



I would not be against such an approach.  Much of the C/C++ stuff is rarely touched.  If we have some source cython that is used to generate C/C++ source code that is packaged in the same way as the current code is, I would have no problem with that.  Given that matplotlib is such a fundamental tool in the ecosystem, I want to make sure that the decisions we make are ones that improves our packaging situation.



Cheers!
Ben Root