code: public void putLogfunc(LogListener listener, Object userhandle) throws LpSolveException {
  		logListener = listener;
  		logUserhandle = (listener != null) ? userhandle : null;
  		addLp(this);
  		registerLogfunc();
  	}
docs: Register an <code>LogListener</code> for callback.
  
  @param listener the listener that should be called by lp_solve
  @param userhandle an arbitrary object that is passed to the listener on call