Dynamic types, pattern subscribing. and more.

Apart from improving Message Queuing when the device is not connected with Grandeur this release introduces the following major changes:

1. Dynamic Type Var

We added a dynamic type Var. You can literally do the following in your arduino sketch now:

Var x = true;
Serial.printf("I am a bool: %d.\n", x);
x = 75;
Serial.printf("I am an int: %d.\n", x);
x = "I am a string";
Serial.println(x);

You can use Var to store JSON objects as well:

Var json;
json["current"] = 10;
json["voltage"]["vpp"] = 440;
json["voltage"]["vpeak"] = 220;
Serial.println(JSON.stringify(json));
/** Prints:
{
  "current": 10,
  "voltage": {
    "vpp": 440.
    "vpeak": 220
  }
}
*/

2. Update in callback for device.data().on() function

device.data().on() function now accepts callback function of void(*)(Var data, const char* path) type not void(*)(JSONObject). In place of Var, you can use any type (int, const char*, String, bool, etc). device.data().get() and device.data().set() still accept callback function of void(*)(JSONObject) type.

void handleUpdate(int voltage, const char* path) {
  Serial.printf("%s got updated. New voltage is: %d.\n", path, voltage);
}
device.data().on("voltage", handleUpdate);

3. Pattern Subscribing

You can now pattern subscribe device variables. For example, for following device data:

{ "voltage": { "vpp": 440, "vpeak": 220 }, "current": 10 }

You can subscribe to both vpp and vpeak by subscribing to the parent, voltage, that is, by doing:

device.data().on("voltage", /**UpdateHandler**/)