Transitive Const in OO programming

[Alex Burton]

Sean Kelly Wrote:

> Alex Burton wrote:
> > Regan Heath Wrote:
> > 
> >> 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.
> 
> Because getResult modifies the state of the object?  Given this 
> particular use case, I think I'd want to be aware of the 'destructive' 
> behavior of getResult.  I have found uses for 'mutable' in the past, but 
> mostly for things like mutexes for synchronizing data access rather than 
> the data itself.
> 
I don't use c++ mutable either, except sometimes in tests.
The key thing here is that I am not 'modifying the state of the object', I am modifying the state of another object I just happen to be maintaining a reference to.
There is nothing to say that StateMachine is part of StateMachineWrapper.

Alex