angular2 - Execute template statement from directive

Question

I basically want what having an

@Ouput() private event = new EventEmitter<any>();

does except I need to be able to capture the return value from that statement.

I want to pass the directive a function call that will execute on click and I want the directive to be able to use the return value from that function.

Currently the way I've gotten it working is by passing it as such

<button [myDirective]='[theFunction, param1, param2]'></button>

but I would like to be able to do

<button myDirective='theFunction(param1, param2)'></button>

In angular 1 you were able to do this using $eval on the string that's passed in. How do you do this in angular 2?