enum sub-range in ADA

Question

In existing ADA code, I found these two lines:

type SWITCH_TYPE is (TI1, TO3, TI2, TO1, TI3, TO2);
subtype TI_SWITCH_TYPE is SWITCH_TYPE range TI1..TI2;
subtype TO_SWITCH_TYPE is SWITCH_TYPE range TO1..TO2;

Is TO3 part of the TI_SWITCH_TYPE? Similarly, is TI3 part of TO_SWITCH_TYPE?

Answer 1

Yes, they are. The enum values are ordered in the way they are defined and you can have ranges like that. The names are of no consequence to the ordering.

Answer 2

As above, but know that with Ada 2012, one can even define non-contiguous enumeration subtypes, e.g.:

type Animal is
 (Bear, Cat, Dog, Wolf, Horse);

subtype Pet is Animal
   with Static_Predicate => Pet in Cat | Dog | Horse;

Ada Rationale discussion on Subtype Predicates.