xtd.delegates - Reference Guide  0.0.1
Modern c ++ 17 library containing delegate which is a data structure that refers to a static method or to a class instance and an instance method of that class.

§ empty

const event_args xtd::event_args::empty
static

Provides a value to use with events that do not have event data.

Remarks
Pass this value to event handlers that are associated with events that do not have data.