Re: types and subtypes

[Jean-Pierre Rosen <rosen@adalog.fr>]

ada_student@yahoo.com a �crit :
>> Because they are of the same *type*. A subtype does not declare a
>> different type, only a restriction (a *constraint*) on the allowed
>> values. Since the types are the same, the declaration is OK.
>>
> 
> Then Ada's definition of a type is different from other languages.
No, Ada's definition of a *sub*type is different.

> A type also defines the set of values that an object can have.
That's correct.

In other languages, a subtype is a sub-type, i.e. a type "sub" (under) 
another type.

In Ada, a type is a set of value; a subtype is a subset of that set. 
Since a subset is included in the set, a subtype is included in (and of 
same nature as) the type.

-- 
---------------------------------------------------------
            J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr