Transitive Const in OO programming

[Alex Burton]

Regan Heath Wrote:

> StateMachine::getResult modifies state and cannot be 'const' either.  In 
> this case I think you need a non-const StateMachine::reset to go back to 
> state = 0;  It makes sense, especially if you want to call getResult 
> several times for example.
> 
> Why call StateMachine::sendMessage inside stateMachineWrapper::getResult?

Because it's a state machine and thats how it works.

> Why does StateMachineWrapper::getResult have to be const?

All it does is gets a value - the fact that internally perhaps several layers of code down there is a state machine should not make a nice get method become non const, and in turn prevent it from being used from a const method.

> It seems making StateMachineWrapper::getResult non-const solves the problem.

Yes it would but then I can't simply call a get method (getResult) using a const reference to StateMachineWrapper.

> Regan

Thanks for your reply Regan, but I think you misunderstand my post, this is not a specific programming problem I have, it is some code I have constructed in order to illustrate a conceptual problem.

Alex