Question

Type typeThing = gumballMachine.GetState().GetType();
if (typeThing == typeof(NoQuarterState)) { ... }


IState state;
public IState GetState() {
    return state;
}


public class NoQuarterState : IState { ... }

I’m using a gumballMachine app from Ch10 of Head First Design Patterns. full code here This works.

Problem: typeThing above smells! Is there a better way?

Answer 1

You could use the is operator:

if(gumballMachine.GetState() is NoQuarterState)
{
   //..
}

This of course would result in true for all types that inherit from NoQuarterState as well though. Based on your example this shouldn’t be a problem.

The question is why do you have to distinguish by type in the first place? Usually that’s a sign that a better design is in order, i.e. maybe the the strategy pattern or another use of polymorphism could help.