Re: [Swig-user] Compilation errors when wrapping methods returning typedefs of same primitive type

[Botos, C. <cb...@ae...>]

On 11/15/11, William S Fulton  <ws...@fu...> wrote:
> On 15/11/11 15:29, Botos, Christopher wrote:
> >Hi,
> >
> >I have been unsuccessful at getting this somewhat complex file to
> >compile (at least it seems complex to me!).
> >
> >I have a class called DoubleBlocks that has methods returning a
> >std::list of type DoubleBlock1 or DoubleBlock2:
> >
> >    std::list<DoubleBlock1> readDoubleBlocks1() const;
> >    std::list<DoubleBlock2> readDoubleBlock21() const;
> >
> >
> >DoubleBlock1 and DoubleBlock2 are typedefs of templated class
> >DataBlock<T>, where T in each case is a typedef of a double, like this.:
> >
> >    typedef double Double1;
> >    typedef double Double2;
> >
> >    typedef DataBlock<Double1> DoubleBlock1;
> >    typedef DataBlock<Double2> DoubleBlock2;
> >
> >
> >The .i file portion that deals with this is below.  From Python, I need
> >to be able to use the methods to get the list of DoubleBlocks, get each
> >DoubleBlock from the list, and use DoubleBlock methods to get data from
> >them, which are doubles.
> >
> >When I compile the .cxx, I get the following errors:
> >
> >    DoubleBlocks_wrap.cxx:4126: error: previous definition of âstruct
> >    swig::traits<NS1::NS2::NS3::DataBlock<double> >â
> >    DoubleBlocks_wrap.cxx:4332: error: redefinition of âstruct
> >    swig::traits<std::list<NS1::NS2::NS3::DataBlock<double>,
> >    std::allocator<NS1::NS2::NS3::DataBlock<double> > > >â
> >    DoubleBlocks_wrap.cxx:4232: error: previous definition of âstruct
> >    swig::traits<std::list<NS1::NS2::NS3::DataBlock<double>,
> >    std::allocator<NS1::NS2::NS3::DataBlock<double> > > >â
> >    make: *** [DoubleBlocks_wrap.o] Error 1
> >
> >
> >*However* if I delete (comment out) either of what I labelled the
> >Double1 section or Double2 section of the .i file, then the one that
> >remained compiles fine and I'm able to manipulate those objects just
> >fine in Python.
> >
> >begin DoubleBlocks.i
> >============================================
> >%module DoubleBlocks
> >%{
> >#define SWIG_FILE_WITH_INIT
> >#include "DataBlock.h"
> >#include "DoubleBlock1.h"
> >#include "DoubleBlock2.h"
> >using namespace NS1::NS2::NS3;
> >%}
> >
> >%include "std_list.i"
> >%include "DataBlock.h"
> >
> >//-------------------------------------------------------------------------
> >// Double1
> >// std::list<DoubleBlock1> readDoubleBlocks1() const;
> >namespace NS1 {
> >namespace NS2 {
> >namespace NS3 {
> >typedef NS1::NS2::NS3::DataBlock<NS1::NS2::NS3::Double> DoubleBlock1;
> >typedef std::list<NS1::NS2::NS3::DataBlock<NS1::NS2::NS3::Double> >
> >DoubleBlock1_List;
> >}}}
> >
> >%typemap(out) NS1::NS2::NS3::Double1& { $result =
> >PyFloat_FromDouble((double) *$1); }
> >%template(DoubleBlock1) NS1::NS2::NS3::DataBlock<NS1::NS2::NS3::Double1>;
> >%template(DoubleBlock1_List) std::list<NS1::NS2::NS3::DoubleBlock1>;
> >
> >//-------------------------------------------------------------------------
> >// Double2
> >// std::list<DoubleBlock2> readDoubleBlocks2() const;
> >namespace NS1 {
> >namespace NS2 {
> >namespace NS3 {
> >typedef NS1::NS2::NS3::DataBlock<NS1::NS2::NS3::Double2> DoubleBlock2;
> >typedef std::list<NS1::NS2::NS3::DataBlock<NS1::NS2::NS3::DoubleBlock2>
> > > DoubleBlock2List;
> >}}}
> >
> >%typemap(out) NS1::NS2::NS3::Double2& { $result =
> >PyFloat_FromDouble((double) *$1); }
> >%template(DoubleBlock2) NS1::NS2::NS3::DataBlock<NS1::NS2::NS3::Double2>;
> >%template(DoubleBlock2List) std::list<NS1::NS2::NS3::DoubleBlock2>;
> Avoid using typedefs for the template parameters in %template. I've some fixes in progress so this will work better, but for now you probably need:
> 
> %template(DoubleBlock2) NS1::NS2::NS3::DataBlock< double >;
> %template(DoubleBlock2List) std::list< double >;
> 
> which if I've read your code correctly is correct as all that verbiage is actually a double!
> 
> William
> 

Thanks so much for your reply, William.  I realize everything comes down to doubles, but the C++ code uses typedefs everywhere.  I unfortunately have no control over any of the C++ implementation.

If I understand your suggestion correctly, then
"%template(DoubleBlock2List) std::list< double >"   
should actually be
"%template(DoubleBlock2List) std::list<NS1::NS2::NS3::DataBlock<std::list< double > >"   

If I do that, then when I run the code (AND I comment everything about Double1) I get a runtime error when Python tries to get the DoubleBlock2 from the list:
  ...
  datablock = datablock[0]
TypeError: 'SwigPyObject' object is unsubscriptable
swig/python detected a memory leak of type 'NS1::NS2::NS3::DoubleBlock2List *', no destructor found.

But then if I return to using the typedefs in the %template parameters it runs fine.
BUT then, again, if I uncomment the Double1 code, I get back the compile error.

Chris



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