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From: steve.folly@rdel.co.uk (Steve Folly)
Subject: Access to strings and string subtypes?
Date: 2000/03/16
Message-ID: <38d10a7b.91796987@news.rrds.co.uk>#1/1
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Organization: RDEL
NNTP-Posting-Date: 16 Mar 2000 16:33:49 GMT
Newsgroups: comp.lang.ada
Date: 2000-03-16T16:33:49+00:00
List-Id: <comp.lang.ada>

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.