A non-exception Value<T> alternative for unions

[gavinSteyn]

I'd like to be able to get the Value of a union using the syntax of Value() (i.e. using the class name), but without the risk of throwing an exception. I have 3 approaches in mind, and before I start coding I was hoping you could weigh in on which way I should go.

1. Add a Option<T> GetValue<T>() which returns Some if the union is of type T, else None
2. Add a bool TryGetValue<T>(out value) which returns a bool as to whether it succeeded and the actual value in the out param
3. Add a bool HasValue<T>() which just returns a bool for whether this union is of type T

Do you have a preferred approach?

Thank you, Gavin Steyn

[DavidArno]

Putting a checklist here to keep track of adding this to the new v4:

• [x] Use the names CaseOf<T>(), TryCaseOf<T>() and HasCaseOf<T> to better fit with other such methods.
• [x] Add a HasCase(Variant variant) method too
• [x] Add to Union<T1, T2>
• [x] Add to Union<T1, T2, T3>
• [x] Add to Union<T1, T2, T3, T4>
• [ ] Document

[DavidArno]

Need to add details of these methods to the wiki now that v4 is released.