Re: IBM 437 encoded String to UTF-16 Wide_String

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Thu, 29 Nov 2012 15:05:19 +0100, Georg Bauhaus wrote:

> On 29.11.12 11:52, Dmitry A. Kazakov wrote:
>> On Thu, 29 Nov 2012 10:51:27 +0100, Georg Bauhaus wrote:
>> 
>>> - if I want my subprograms to work with different
>>>    types of strings,
>> 
>> type A is new B; -- Ada 83
> 
> type A is new Root_String'Class;  -- not Ada

Rather:

   type My_Incompatible_String is new String; -- Ada 83

Yes, Ada 95 broke that for tagged typed. Presently, the workaround is this:

   type Base is abstract tagged ...;
   -- Define operations to clone here

   type A is new Base with null record;
   type B is new Base with null record;

Now B has the semantics of cloned A.

   type B is new A;

In any case, you cannot clone classes, you should their root types instead.
That will have the effect of cloning the class.

>>> this particular kind of problem can be solved with the help of a
>>> generic formal package that a user of my programs has instantiated,
>> 
>> Egh, which problem?
> 
> That of making a subprograms work with any type of
> string in current Ada.

And how generic container library may help? Generic instances do not
comprise a run-time class, which is their major flaw.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de