Access to strings and string subtypes?

[steve.folly@rdel.co.uk (Steve Folly)]

Could someone explain why this code doesn't work.
I know the LRM reference that prevents it, but, in laymans terms, please explain
*why* :-)

package Test is

   type Ref is access all String;

   subtype Name is String(1..10);
   type Name_Ref is access all Name;

   A : aliased Name;
   C : aliased String (1..10);

   D : Name_Ref := A'Access; -- OK
   E : Ref := A'Access; -- Does not statically match designated subtype ???
   F : Ref := C'Access; -- Does not statically match designated subtype ???

   G : Ref := new String'("THIS WORKS"); -- OK!

end Test;


I would have expected a Ref type to be able to point to any constrained string
type. Why are subtypes not allowed?

We have various classes defined with strings of different sizes, but would like
a single function to be able to take any one of these strings and manipulate it,
possibly changing it's contents.


Thanks.

Steve Folly.