[Newbie] doubly constrained array, dumb question

[Mehdi Saada <00120260a@gmail.com>]

Hello.

I would like an constrained String subtype with narrower bounds that Positive'Range.
How can I do something like:
subtype Possible_Length is NATURAL range 1..80;
subtype T_Line is String (Possible_Length range <>);
? I know "range <>" isn't included in the definition of "range_constraint". How can I express the same thing.
So that I can get after, a dynamic string with:
A: access T_LINE := new T_LINE'("BLABLABLA"); while checking for its range.

Thanks, Mehdi
Mehdi