[Numpy-discussion] numpy 2.0, what else to do?
Charles R Harris
charlesr.harris at gmail.com
Tue Feb 16 00:52:27 EST 2010
On Mon, Feb 15, 2010 at 10:35 PM, Charles R Harris <
charlesr.harris at gmail.com> wrote:
>
>
> On Mon, Feb 15, 2010 at 10:19 PM, David Cournapeau <david at silveregg.co.jp>wrote:
>
>> Charles R Harris wrote:
>> >
>> >
>> > On Mon, Feb 15, 2010 at 8:13 PM, David Cournapeau <
>> david at silveregg.co.jp
>> > <mailto:david at silveregg.co.jp>> wrote:
>> >
>> > Charles R Harris wrote:
>> > >
>> > >
>> > > On Mon, Feb 15, 2010 at 3:58 PM, Charles R Harris
>> > > <charlesr.harris at gmail.com <mailto:charlesr.harris at gmail.com>
>> > <mailto:charlesr.harris at gmail.com
>> > <mailto:charlesr.harris at gmail.com>>> wrote:
>> > >
>> > >
>> > >
>> > > On Mon, Feb 15, 2010 at 3:34 PM, David Cournapeau
>> > > <cournape at gmail.com <mailto:cournape at gmail.com>
>> > <mailto:cournape at gmail.com <mailto:cournape at gmail.com>>> wrote:
>> > >
>> > > On Tue, Feb 16, 2010 at 7:04 AM, Charles R Harris
>> > > <charlesr.harris at gmail.com
>> > <mailto:charlesr.harris at gmail.com> <mailto:
>> charlesr.harris at gmail.com
>> > <mailto:charlesr.harris at gmail.com>>>
>> > > wrote:
>> > > >
>> > > >
>> > > > On Mon, Feb 15, 2010 at 2:46 PM, David Cournapeau
>> > > <cournape at gmail.com <mailto:cournape at gmail.com>
>> > <mailto:cournape at gmail.com <mailto:cournape at gmail.com>>>
>> > > > wrote:
>> > > >>
>> > > >> On Tue, Feb 16, 2010 at 4:08 AM, Charles R Harris
>> > > >> <charlesr.harris at gmail.com
>> > <mailto:charlesr.harris at gmail.com>
>> > > <mailto:charlesr.harris at gmail.com
>> > <mailto:charlesr.harris at gmail.com>>> wrote:
>> > > >>
>> > > >> >
>> > > >> > I was wondering about that. Why do we have a
>> private
>> > > include directory?
>> > > >> > Would it make more sense to move it to
>> > > core/include/numpy/private.
>> > > >>
>> > > >> No, the whole point is to avoid other packages to
>> include
>> > > that by
>> > > >> mistake, to avoid namespace pollution.
>> > > >
>> > > > Isn't that what the npy prefix is for?
>> > >
>> > > No, npy_ is for public symbols. Anything in private
>> should be
>> > > private :)
>> > >
>> > > > In any case, if it needs to be at a
>> > > > higher level for easy inclusion, then it should move
>> up.
>> > >
>> > > It is not that easy - we should avoid putting this code
>> into
>> > > core/include, because then we have to keep it compatible
>> > across
>> > > releases, but there is no easy way to share headers
>> > between modules
>> > > without making it public.
>> > >
>> > >
>> > > Py_TYPE, Py_Size, etc. are unlikely to cause compatibility
>> > problems
>> > > across releases.
>> > >
>> > >
>> > >
>> > > In particular, I think
>> > >
>> > > #if (PY_VERSION_HEX < 0x02060000)
>> > > #define Py_TYPE(o) (((PyObject*)(o))->ob_type)
>> > > #define Py_REFCNT(o) (((PyObject*)(o))->ob_refcnt)
>> > > #define Py_SIZE(o) (((PyVarObject*)(o))->ob_size)
>> > > #endif
>> > >
>> > > belongs somewhere near the top, maybe with a prefix (cython seems
>> to
>> > > define them also)
>> >
>> > The rule is easy: one should put in core/include/numpy whatever is
>> > public, and put in private what is not.
>> >
>> > Note that defining those macros above publicly is very likely to
>> cause
>> > trouble because I am sure other people do define those macros,
>> without
>> > caring about polluting the namespace as well. Given that it is
>> > temporary, and is small, I think copying the compat header is better
>> > than making it public, the best solution being to add something in
>> > distutils to share it between submodules,
>> >
>> >
>> > You would prefer to fix the macros in ndarrayobject.h using #ifdef's
>> then?
>>
>> In case what I am worried about is not clear: if ndarrayobject.h defines
>> Py_TYPE, it means that every C extensions using the numpy C API will
>> have Py_TYPE in the public namespace. Now, if another python extension
>> with a C API does the same, you have issues. Having #ifdef/#endif around
>> only make it worse because then you have strange interactions depending
>> on the order of header inclusion (I really hate that behavior from the
>> python headers).
>>
>> The numpy C headers are already pretty messy, let's not make it worse.
>> Especially since the workaround is trivial.
>>
>>
> What is the work around? Mind, I think those macros need to be compatible
> with py3k just to make porting other applications easier. I still think we
> should call it NPY_Py_TYPE or some such. We also have some stray ob_refcnt.
> Note that the gnu headers also have implementation stuff hidden away in a
> folder. Whatever we do, I think it needs to be easy discover for anyone
> coming new to the code, it shouldn't be hidden away in somewhere in the
> distutils. That's like burying it on a small Caribbean island along with all
> the witnesses.
>
>
Just to be clear, there are *already* macros in the ndarrayobject.h file
that aren't py3k compatible. How do you propose to fix those?
Chuck
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