[Cython] Add includes to generated header files

[Jeff Copeland]

On Thu, Aug 2, 2012 at 8:43 PM, Stefan Behnel <stefan_ml at behnel.de> wrote:
> Jeff Copeland, 03.08.2012 02:18:
>> I'm working on some C++ projects and I'm using cython to embed python
>> code.  In an effort to make things easy for C++ devs not as familiar
>> with cython/python I've made a small change to insert #includes in
>> generated header files the same as is done in generated c code.  This
>> allows one who is using code processed with cython to just include the
>> header and not worry about any other headers that may be required to
>> match data types.
>>
>> Not having these headers is especially problematic because otherwise
>> the error message presented at compilation can sometimes be quite
>> cryptic.
>>
>> Patch is attached.  Any reason this should not be done?
>
> Hmm, didn't try your patch, but I guess it inserts includes for *all*
> header files that the module that exports the C-API uses internally, right?

Yes, you've got it.  Certainly quick and dirty to satisfy my immediate need.

> If so, I'm not sure that's always wanted. I see the advantage, sure, but it
> may expose a lot of implementation details that external code may not
> normally have to care about.
>
> On the other hand, if extension types are exported, for example, it's
> somewhat unlikely that their struct would compile without at least some of
> those header files, because they almost always wrap some kind of externally
> defined struct, pointer or whatever kind of other data type.

Exactly.

> That sounds to me like we should make it a configurable option, something
> like "capi_reexport_cincludes".

I like that thought.  The other thing I'd though of is perhaps some
syntax in the pyx itself to designate an include file as one that
should show in a generated header.  When I was looking for a solution
to the issue that's what I started looking for in the documents but of
course came up empty.  I figured it may be something like the case for
inclusion in the c file but with a public/api keyword thrown in:

cdef extern public from "spam.h":
    pass

Syntax change would probably be more involved.  I'll have a go at
doing a patch with the option added.  Do you mean as a command-line
option to cython?

Jeff