add listeners() impl

events.h

@@ -29,12 +29,16 @@ class EventEmitter {
     return static_cast<typename traits<Callback>::fn>(cb);
   }
 
-  int listeners = 0;
+  int _listeners = 0;
 
   public:
 
     int maxListeners = 10;
 
+    int listeners() {
+      return this->_listeners;
+    }
+
     template <typename Callback>
     void on(std::string name, Callback cb) {
 
@@ -43,10 +47,10 @@ class EventEmitter {
         throw new std::runtime_error("duplicate listener");
       }
 
-      if (++this->listeners >= this->maxListeners) {
+      if (++this->_listeners >= this->maxListeners) {
         std::cout 
           << "warning: possible EventEmitter memory leak detected. " 
-          << this->listeners 
+          << this->_listeners 
           << " listeners added. "
           << std::endl;
       };
@@ -64,6 +68,7 @@ class EventEmitter {
 
     void off() {
       events.clear();
+      this->_listeners = 0;
     }
 
     void off(std::string name) {
@@ -72,6 +77,7 @@ class EventEmitter {
 
       if (it != events.end()) {
         events.erase(it);
+        this->_listeners--;
 
         auto once = events_once.find(name);
         if (once != events_once.end()) {

test.cc

@@ -71,6 +71,8 @@ int main (int argc, char* argv[]) {
     count3++;
     ASSERT("events were fired even though all listeners were removed", false);
   });
+
+  ASSERT("the correct number of listeners has been reported", ee.listeners() == 4);
 
   ee.off();