Calculate when event is fired

[OrkhanGG]

Can we get nodes to calculate when events are fired without changing the engine too much?

I think everything is obvious enough but I'll show an example to make it even clearer:

As you can see from the example above, generate should be triggered when "pressed" output is fired. So, is it possible?
And if so, can we block a connection? With something like an open-close gate node?