spark/firmware — pull request #314 by rastapasta (2014-09-17 17:11:17+00:00)
Title: Adding possibility for callback value registraion with Spark::function

...allowing implementations of function calls to class members, should resolve #313

Allows following pattern as mentioned by @m-mcgowan on this thread: http://community.spark.io/t/how-to-point-spark-function-to-a-class-function/6986/4

```cpp
class MyClass {
static int callback(String arg, void* pv) {
return ((MyClass*)pv)->handle(arg);
}

virtual int handle(String arg) {
return 42;
}
}

MyClass my_class;
Spark.function("myfunc", MyClass::callback, &my_class);
```