Design Case: Which approach is better?

Hello all,

I want opinions on which approach is better from software design perspective. Here is the case details:

I have three classes: State, StateMachine and Handler. StateMachine passes a State pointer to Handler. Handler can manipulate certain data within State, but SHOULD NOT modify the rest.

Thanks,
Sarmad

It might help if you provided an example of the problem you're trying to solve... the design pattern relationships are a bit ambiguous w/o a use case to contextualize them.