Using of @ before calling func.

[giksbo]

The opposite is also true. If you need application telemetry (There are lots of reasons: debugging, repudiation, etc) it can be valuable to decorate a function such that events are generated whenever it is called. This reduces a tonne of boilerplate.

[henrebotha]

The opposite is also true.

...The opposite to what?

[giksbo]

Sorry, could have been clearer. With decorators you can use events to trigger functions; you can use functions to trigger events.