[Swig-user] SWIG C++/Java inheritance issues

[Stanford, E. R. <Edw...@it...>]

I am having trouble accessing inherited C++ class members in a C++ library (but not regular class members) via SWIG from Java.  I am using SWING 1.3.40, and have reduced my problem to the following test case:

C++ .h files

Parent.h
   class Parent
   {
   public:
        Parent(): str("parent") {};
        virtual ~Parent();

        std::string get() { return str; }

   private:
        std::string str;
   };

Child.h
   class Child : public Parent
   {
   public:
        Child(): bar("child") {};
        virtual ~Child();
        std::string getBar() { return bar; }
   private:
        std::string bar;
   };

Thus, on the C++ side I can make a call to get() from an instance of Child and get the std::string "bar", or a call to getBar() and get the std::string "dang It".  I wish to achieve similar functionality in Java.

I generate the proxy classes via the following SWIG command:

   swig -Wall -c++ -java -package com.itt.cudadif -outdir com/itt/cudadif -module cudadif cudadif.i

using the following interface file:

%module cudadif

%include "arrays_java.i";
%include std_string.i

%ignore *::operator+=;
%ignore *::operator=;
%ignore *::operator+;
%ignore *::operator!=;
%ignore *::operator==;

%{
#include "Parent.h"
#include "Child.h"
%}

%include ../cushark/DeviceBenchmark.h
%include ../cushark/CudaMetaData.h
%include Parent.h
%include Child.h

Shared objects and proxy classes are duly generated. When I attempt to use the resulting classes from java 1.6.0_20, I use the following test driver:

import com.itt.cudadif.Parent;
import com.itt.cudadif.Child;

public class Driver
{
    public static void main(String argv[])
    {
        System.loadLibrary("cudadifjni");

        Parent ts = new Parent();

        String ss = ts.get();

        System.err.println(ss);

        Child us = new Child();

        System.err.println("Should work " + us.getBar());

        System.err.println("Child calls parent");

        System.err.println(us.get());
}

The result compiles, and runs properly until the last line, as can be seen from the following output:

parent
Should work child
Child calls parent
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007fd878b68778, pid=6085, tid=140568964585744
#
# JRE version: 6.0_20-b02
# Java VM: Java HotSpot(TM) 64-Bit Server VM (16.3-b01 mixed mode linux-amd64 )
# Problematic frame:
# C  [libstdc++.so.6+0xa6778]  _ZNSsC1ERKSs+0x8

I appear to be able to access get() from an instance of Parent, but not the get() method an instance of Child should inherit.

If it matters, I am on Ubuntu 9.10, running gcc 4.3.4.

Any suggestions would be most welcome.

Edward

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