[Insight-developers] help with wrapping wrap_itkWatershedImageFilter

[Brad King]

Charl P. Botha wrote:

> Dear developers,
> 
> I'm trying to wrap the itkWatershedImageFilter class.  After having created 
> the attached wrap_itkWatershedImageFilter.cxx file in the Wrapping/CSwig/
> Algorithms directory and having made the changes shown in the attached diff 
> file, I get the following build errors on Debian Stable, g++ 2.95.4:
> 
> Building wrap_itkWatershedImageFilter.xml from  /home/cpbotha/DoNotBackup/
> build/Insight-gcc/Wrapping/CSwig/Algorithms/
> wrap_itkWatershedImageFilter.xml...
> In file included from /home/cpbotha/DoNotBackup/build/Insight/Code/Algorithms/
> itkWatershedBoundary.h:30,
> from /home/cpbotha/DoNotBackup/build/Insight/Code/Algorithms/
> itkWatershedSegmenter.h:25,
> from /home/cpbotha/DoNotBackup/build/Insight/Code/Algorithms/
> itkWatershedImageFilter.h:26,
> from /home/cpbotha/DoNotBackup/build/Insight/Wrapping/CSwig/Algorithms/
> wrap_itkWatershedImageFilter.cxx:18:
> /home/cpbotha/DoNotBackup/build/Insight/Code/Common/itk_hash_map.h:112: error: 
> ISO C++ forbids declaration of `select1st' with no type
> /home/cpbotha/DoNotBackup/build/Insight/Code/Common/itk_hash_map.h:112: error: 
> template-id `select1st<pair<const Key, T> >' used as a declarator
> /home/cpbotha/DoNotBackup/build/Insight/Code/Common/itk_hash_map.h:112: error: 
> syntax error before `;' token
> 
> Does anyone have any ideas?  As far as I can see, "select1st" is declared in 
> the stl_function.h on my system.  "functional", which includes 
> stl_function.h, is included somewhere in the itk_hash_map.h hierachy.

The problem is that GCC 2.95 has the fake std namespace hack, but 
GCC-XML uses GCC 3.3's parser which does not have the hack.  There is a 
directory in GCC-XML that contains header wrappers to move all standard 
library symbols into the std namespace with using declarations.  Since 
select1st and select2nd are not actually part of the C++ standard, these 
symbols were not included when I made a sweep through the standard to 
list all symbols.  I've committed a fix to the header wrapper for 
functional that includes these symbols.  The fix is on the main tree and 
in the ITK 1.6 branch of CableSwig.

-Brad