How to check if a callback is defined (not empty)?

[showier-drastic]

I'm making a button-like component. I would like to render the button as disabled, if a callback is not passed in. Is this possible?

[ogoffart]

right now this is not possible.
You need an extra property for that.

I'm thinking we might want to have a way to detect that. This could be useful for optimization as well.