/** A Debug class for which output can be easily switched on/off.
 * The method "print" will print a message,
 * only if "on" is set (default: true).
 * You can use setLog() to specify a file output (default: System.out).
 *  Warning!: setLog(String) will trash any previously-existing file!
 */
class Debug {
  public static boolean on = true;
  protected static java.io.PrintStream dest = System.out;
  
  /** Warning: calling setLog(String) trashes any previously-existing file,
   * even if it was one created during this same run of the program.
   */
  public static void setLog( java.io.PrintStream out ) { dest = out; }
  public static void setLog( String filename ) throws java.io.IOException {
    setLog( new java.io.PrintStream(
	      new java.io.FileOutputStream(
                new java.io.File( filename ) ) ) );
    }

  public static void print(String s) {
    if (on) dest.println(s);
  }

 
  /* Testing...
   */
  public static void main( String[] args ) throws java.io.IOException {
    Debug.on = false;
    Debug.print( "A test which should not be printed." );
    Debug.on = true;
    Debug.print( "A test which should be printed." );

    // Switch output to a file.
    String testOutFile = "foo.out";
    Debug.setLog( testOutFile );

    Debug.on = false;
    Debug.print( "A test which should not be filed." );
    Debug.on = true;
    Debug.print( "A test which should be filed." );

    // Switch back to System.out:
    Debug.setLog( System.out );
    Debug.print( "Bye." );
    
  }
}