Re: [Swig-user] nested class in std::vector

[Dieter V. <dva...@ax...>]

On Sun, 2010-04-18 at 04:01 -0400, William S Fulton wrote:
> Dieter Vandenbussche wrote:
> > Hi, i've run into a problem when trying to iterate (in Python) over a
> > proxy of a vector containing a C++ class that is nested in another
> > class.
> > 
> > Here's the example:
> > 
> > /* InnerOuter.h"/
> > #include <vector>
> > 
> > class Outer { 
> >    public:
> >       class Inner { 
> >          public:
> >             double v_;
> >             Inner(double v = 0.0): v_(v) {}
> >       };
> > 
> >       std::vector<Inner> getSomeInners() { 
> >          std::vector<Inner> result;
> >          result.push_back(Inner(1.0));
> >          result.push_back(Inner(2.0));
> >          return result;
> >       };
> > };
> > 
> > /* InnerOuter.i*/
> > %module innerouter
> > 
> > %include stl.i
> > 
> > %feature("autodoc", "1");
> > 
> > %{
> > #include <vector>
> > #include "InnerOuter.h"
> > %}
> > 
> > namespace std {
> >    %template(VectorInner) vector<Outer::Inner>;
> > };
> > 
> > class Inner {
> >    public:
> >       double v_;
> >       Inner(double v);
> > };
> > 
> > %{
> > typedef Outer::Inner Inner;
> > %}
> > 
> > class Outer {
> >    public:
> >       std::vector<Inner> getSomeInners();
> > };
> > 
> > When i run the following python code:
> > from innerouter import *
> > 
> > x = Outer()
> > z = x.getSomeInners()
> > 
> > for y in z:
> >    print y.v_
> > 
> > #for i in xrange(len(z)):
> > #   print z[i].v_
> > 
> > I get this error:
> > Traceback (most recent call last):
> >   File "mytest.py", line 7, in <module>
> >     print y.v_
> > AttributeError: 'SwigPyObject' object has no attribute 'v_'
> > swig/python detected a memory leak of type 'unknown', no destructor
> > found.
> > 
> > Running the commented code works fine, so i have a workaround, but 
> > i thought this might be a helpful test case.  I know nested classes are
> > not fully supported, so i can understand if it is nontrivial to resolve
> > this.
> > 
> You need to put the %template at the end. Also note with swig-2.0.0 due 
> out shortly you can instead use the %nestedworkaround feature as follows:
> 
> %include stl.i
> 
> %feature("autodoc", "1");
> 
> %{
> #include <vector>
> #include "InnerOuter.h"
> %}
> 
> %nestedworkaround Outer::Inner;
> 
> class Inner {
>     public:
>        double v_;
>        Inner(double v);
> };
> 
> %include "InnerOuter.h"
> 
> %{
> typedef Outer::Inner Inner;
> %}
> 
> namespace std {
>     %template(VectorInner) vector<Outer::Inner>;
> };
> 
> William

Hi William, you responded to this quite a while ago but i hadn't had
time to look back into it, my apologies.  

While i did find that the %nestedworkaround on swig-2.0 resolved this
issue, i was not able to get things to work with swig 1.3.40 by moving
the template to the end of the file.  I still got the same error
message.