Implementation of a generic CallBackList (#5710)

* Initial version

Move to experimental namespace

Change namespace

libraries/esp8266/examples/CallBackList/CallBackGeneric.ino

@@ -0,0 +1,64 @@
+#include <Arduino.h>
+#include <Ticker.h>
+#include "CallBackList.h"
+
+using namespace experimental::CBListImplentation;
+
+class exampleClass {
+  public:
+    exampleClass() {};
+
+    using exCallBack = std::function<void(int)>;
+    using exHandler  = CallBackList<exCallBack>::CallBackHandler;
+
+    CallBackList<exCallBack> myHandlers;
+
+    exHandler setHandler(exCallBack cb) {
+      return myHandlers.add(cb);
+    }
+
+    void removeHandler(exHandler hnd) {
+      myHandlers.remove(hnd);
+    }
+
+    void trigger(int t) {
+      myHandlers.execute(t);
+    }
+};
+
+exampleClass myExample;
+
+void cb1(int in) {
+  Serial.printf("Callback 1, in = %d\n", in);
+}
+
+void cb2(int in) {
+  Serial.printf("Callback 2, in = %d\n", in);
+}
+
+void cb3(int in, int s) {
+  Serial.printf("Callback 3, in = %d, s = %d\n", in, s);
+}
+
+Ticker tk, tk2, tk3;
+exampleClass::exHandler e1 = myExample.setHandler(cb1);
+exampleClass::exHandler e2 = myExample.setHandler(cb2);
+exampleClass::exHandler e3 = myExample.setHandler(std::bind(cb3, std::placeholders::_1, 10));
+
+void setup() {
+  Serial.begin(115200);
+
+  tk.attach_ms(2000, []() {
+    Serial.printf("trigger %d\n", (uint32_t)millis());
+    myExample.trigger(millis());
+  });
+  tk2.once_ms(10000, []() {
+    myExample.removeHandler(e2);
+  });
+  tk3.once_ms(20000, []() {
+    e3.reset();
+  });
+}
+
+void loop() {
+}