[C++-sig] Boost.Python NumPy extension

[Stefan Seefeld]

Hi Alex,

On 09.10.2016 00:40, Alex Mohr wrote:
> Cool!  Sorry, I don't have the expertise to help with the boost.build
> aspect, but I did have some questions and comments regarding the feature.
>
> Does this add a dependency of boost.python on numpy?  We'd love to be
> able to continue use boost.python without a numpy dependency.  We did
> a nontrivial amount of work to remove this dependency in USD
> (openusd.org, https://github.com/PixarAnimationStudios/USD), a C++
> library that provides python bindings via boost.python, so adding it
> back would be a problem for us.
>
> Instead of depending on numpy, we made our array structures implement
> the python buffer protocol.  This lets clients that wish to use numpy
> do so easily, since numpy supports the buffer protocol, but it does
> not burden those that don't with the numpy dependency.  We did this
> manually of course but supporting the buffer protocol would be a cool
> feature for boost.python.

Short answer: The dependency on NumPy is only added to the extension
(compiled into a separate library); Boost.Python without that extension
remains exactly the same.

Somewhat longer answer: it all depends how Boost.Python is installed.
There is a configure flag to decide whether to build with or without
NumPy support. Building with NumPy support will yield two libraries:
libboost_python.so and libboost_numpy.so, so I expect downstream
packagers to wrap both into separate packages. (The new headers are
likewise kept separate for the same reason.)

            Stefan


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