Using renaming declarations to make private subprograms visible

[Matthew Woodcraft <mattheww@chiark.greenend.org.uk>]

Suppose I want a private type that I can convert to a string and back:


package Foo is

   type Token_Type is private;

   function To_Token (Source : String) return Token_Type;

   function To_String (Source : Token_Type) return String;

   [...]

private

   [...]	

end Foo;



Now suppose that (for the moment), I want to implement this type using
an unbounded string. I can make Token_Type a derived type of
Unbounded_String, and use renaming declarations to make some of the
'inherited' subprograms publicly visible:

private

   type Token_Type is new Ada.Strings.Unbounded.Unbounded_String;

   function To_Token (Source : String) return Token_Type
     renames To_Unbounded_String;

    -- No good
   function To_String (Source : Token_Type) return String
     renames To_String;

   [...]


The trouble is, this doesn't work when I want the public name of a
subprogram to be the same as the private name (eg, To_String above), as
my new definition overrides the inherited one, and I end up trying
renaming the function to itself.

Is there any way to make the inherited subprogram publicly visible with
the same name? Or am I better off making Token_Type a record with one
component, rather than a derived type?


-M-