On Sunday 11 December 2005 20:12, Victor Lazzarini wrote:

> Could you post an example?

Here is a simple Java example that works with the current CVS
sources (note that this is not implemented for other languages
yet, and may be changed or removed later). The C++ class it
uses is also included below.

// CallbackExample.java

import csnd.*;

public class CallbackExample {

  // JavaCallbacks is a subclass of CsoundCallbackWrapper that
  // can override the methods MessageCallback(), InputValueCallback(),
  // OutputValueCallback(), and YieldCallback() for defining callbacks

  static class JavaCallbacks extends CsoundCallbackWrapper {
    JavaCallbacks(Csound cs)
    {
      super(cs);
    }
    public int YieldCallback()
    {
      java.lang.System.err.println("Yield called for " + GetCsound() + " !");
      return 1;
    }
    public void MessageCallback(int attr, String msg)
    {
      if (msg.endsWith("\n"))
        java.lang.System.err.print("ATTR: " + attr + "  MSG: " + msg);
      else
        java.lang.System.err.println("ATTR: " + attr + "  MSG: " + msg);
    }
  }

  public static void main(String argv[])
  {
    Csound cs = new Csound();
    // create a callback wrapper object for this instance of Csound
    // note that this will use the host data pointer of 'cs', so the
    // host data cannot be used for other purposes
    JavaCallbacks cb = new JavaCallbacks(cs);
    // enable the callbacks for which there are definitions above
    cb.SetYieldCallback();
    cb.SetMessageCallback();
    // build an argument list from the command line options
    CsoundArgVList args = new CsoundArgVList();
    args.Append("csound");
    for (int i = 0; i < argv.length; i++)
      args.Append(argv[i]);
    // call Compile() to see if the callbacks work
    cs.Compile(args.argc(), args.argv());
    // Reset() must be called before 'cs' or 'cb' is possibly
    // garbage collected, otherwise a crash may occur
    cs.Reset();
    // free memory used by the argument list; this is optional, and
    // would be done automatically when 'args' is garbage collected
    args.Clear();
  }
};

// end of CallbackExample.java

---------------------------------------------------------------------

// callback wrapper class declared in interfaces/cs_glue.hpp

class CsoundCallbackWrapper {
 private:
    CSOUND  *csound_;
 public:
    virtual void MessageCallback(int attr, char *msg)
    {
    }
    virtual MYFLT InputValueCallback(const char *chnName)
    {
      return (MYFLT) 0;
    }
    virtual void OutputValueCallback(const char *chnName, MYFLT value)
    {
    }
    virtual int YieldCallback()
    {
      return 1;
    }
    void SetMessageCallback();
    void SetInputValueCallback();
    void SetOutputValueCallback();
    void SetYieldCallback();
    CSOUND *GetCsound()
    {
      return csound_;
    }
    // --------
    CsoundCallbackWrapper(Csound *csound);
    CsoundCallbackWrapper(CSOUND *csound);
    virtual ~CsoundCallbackWrapper()
    {
    }
};


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