[Swig-user] SWIG, Java and callbacks

[<ha...@po...>]

Hello,

I have a set of functions (pure C) that need to make use of 
callbacks into java code. 
As basis I for my first tries I use the example that comes with the 
tgz of swig-1.31. This example creates a caller object and a 
callback object. The Java code registers the callback at the 
caller. Then the callback can be executed from the C++ code.

To use this mechanism for my C code I see 2 possibilities:
1) Get access to the caller object and use the registered callback.
2) Have a global reference to a callback object and provide a 
separate function to the Caller that sets this global reference.

I hope my understanding is correct so far. However my knowledge of 
C++ is limited and my changes were not successful. 

Here are some snippets for the second approach:

--- example.h

class Callback {
...
}

/* my global reference to the callback */
Callback *myCallback;

class Caller {
..
     void setMyVCallback(Callback *cb) { myCallback = cb;}
}

--- main.java

public class main {

   public static void main(String argv[]) {
     System.loadLibrary("example");
     
     Caller   caller = new Caller();
     
     callback = new JavaCallback();
     caller.setMyCallback(callback);
     caller.call();
   }
}

class JavaCallback extends Callback
{
...
}

---

I am thankful for any pointers.

Ruediger