Add method to return the number of attached listeners. Listeners have become

a much more important feature than they were two years or something ago, and
it's helpful for debugging and exploration to get this important node property
shown in property tree dumps or in the property browser (verbose mode).

diff --git a/simgear/props/props.hxx b/simgear/props/props.hxx
index 12d7ba7986c12662b01b77e571d21a9bca3d1150..41361c9862e392ff4ba7c0ce4a6b69e22e16a216 100644 (file)
--- a/simgear/props/props.hxx
+++ b/simgear/props/props.hxx
@@ -1110,6 +1110,12 @@ public:
   void removeChangeListener (SGPropertyChangeListener * listener);
 
 
+  /**
+   * Get the number of listeners.
+   */
+  int nListeners () const { return _listeners ? _listeners->size() : 0; }
+
+
   /**
    * Fire a value change event to all listeners.
    */