[Numpy-discussion] Should we drop support for "one file" compilation mode?

[David Cournapeau]

On Tue, Oct 6, 2015 at 6:14 PM, Nathaniel Smith <njs at pobox.com> wrote:

> On Tue, Oct 6, 2015 at 10:10 AM, David Cournapeau <cournape at gmail.com>
> wrote:
> >
> >
> > On Tue, Oct 6, 2015 at 6:07 PM, Nathaniel Smith <njs at pobox.com> wrote:
> >>
> >> On Tue, Oct 6, 2015 at 10:00 AM, Antoine Pitrou <solipsis at pitrou.net>
> >> wrote:
> >> > On Tue, 6 Oct 2015 09:40:43 -0700
> >> > Nathaniel Smith <njs at pobox.com> wrote:
> >> >>
> >> >> If you need some npy_* function it'd be much better to let us know
> >> >> what it is and let us export it in an intentional way, instead of
> just
> >> >> relying on whatever stuff we accidentally exposed?
> >> >
> >> > Ok, we seem to be using only the complex math functions (npy_cpow and
> >> > friends, I could make a complete list if required).
> >>
> >> And how are you getting at them? Are you just relying the way that on
> >> ELF systems, if two libraries are loaded into the same address space
> >> then they automatically get access to each other's symbols, even if
> >> they aren't linked to each other? What do you do on Windows?
> >
> >
> > It is possible (and documented) to use any of the npy_ symbols from
> npymath
> > from outside numpy:
> >
> http://docs.scipy.org/doc/numpy-dev/reference/c-api.coremath.html#linking-against-the-core-math-library-in-an-extension
> >
> > The design is not perfect (I was young and foolish :) ), but it has
> worked
> > fairly well and has been used in at least scipy since the 1.4/1.5 days
> IIRC
> > (including windows).
>
> Okay, so just to confirm, it looks like this does indeed implement the
> static linking thing I just suggested (so perhaps I am also young and
> foolish ;-)) -- from looking at the output of get_info("npymath"), it
> seems to add -I.../numpy/core/include to the compiler flags, add
> -lnpymath -L.../numpy/core/lib to the linker flags, and then
> .../numpy/core/lib contains only libnpymath.a, so it's static linking.
>

Yes, I was not trying to argue otherwise. If you thought I was, blame it on
my poor English (which sadly does not get better as I get less young...).

My proposal is to extend this technique for *internal* API, but with the
following differences:
 * the declarations are not put in any public header
 * we don't offer any way to link to this library, and name it something
scary enough that people would have to be foolish (young or not) to use it.

David


> -n
>
> --
> Nathaniel J. Smith -- http://vorpus.org
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