On 2011-09-12 13:10+0100 Andrew Ross wrote:
>
> Alan,
>
> Good idea. I was forgetting that you could redefine macros even after
> they had been used in further #define statements.
Hi Andrew:
I assume you have thoroughly tested that assumption so it must be
true, but that sure seems counter-intuitive to me, and I cannot find a
reference to it. Furthermore, K&H "The ANSI C Programming Language",
p. 89 state "subsequent occurrences of the token name will be replaced
....", and that "subsequent" adjective seems to contradict the assumption.
I now realize my previous idea implicitly depended on this assumption
as well because oct-dlldefs.h modifies other macros within it
depending on OCTAVE_EXPORT, and those won't get changed by my
subsequent OCTAVE_EXPORT redefinition if the assumption is incorrect.
If further testing shows this assumption doesn't really work, then I
suggest a new idea which is we simply replace oct-dlldefs.h with our
own modified version where the replace the present OCTAVE_EXPORT
definition logic with the following logic (similar to what we do in
pldll.h(.in)):
#if defined (_MSC_VER)
// Visual C/C++, Borland, MinGW and Watcom
#if defined ( __VISUALC__ ) || defined ( _MSC_VER ) || defined (
__BORLANDC__ ) || defined ( __GNUC__ ) || defined ( __WATCOMC__ )
#define OCTAVE_EXPORT __declspec(dllexport)
#else
#define OCTAVE_EXPORT
#endif
#elif defined ( __CYGWIN__ )
#define OCTAVE_EXPORT __declspec(dllexport)
#elif defined ( __GNUC__ ) && __GNUC__ > 3
#define OCTAVE_EXPORT __attribute__ ( ( visibility( "default" ) ) )
#endif
#ifndef OCTAVE_EXPORT
#define OCTAVE_EXPORT
#endif
The only further issue is our updated header has to be #included
before any other octave header is #included (if the assumption fails).
In swig use the following directives
%begin %{
#include "oct-dlldefs_modified.h"
%}
to accomplish that. The "#define octave_dlldefs_h 1" in our modified
header that is copied from the original means that further #includes
of oct-dlldefs.h effectively become preprocessor no-ops.
Even if the assumption that the last #define of some token completely
supersedes previous #defines of that token is true so your present
solution works, then I suggest you modify that present solution so you
take full control of OCTAVE_EXPORT redefinition for all platforms
using preprocessor language like what I use above for the hypothetical
oct-dlldefs_modified.h.
Alan
__________________________
Alan W. Irwin
Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
__________________________
Linux-powered Science
__________________________
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