Re: Textedit and txt

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

On Mon, 11 May 2015 10:00:38 -0700 (PDT), Shark8 wrote:

> On Friday, May 8, 2015 at 5:35:52 PM UTC-6, Randy Brukardt wrote:
>> "Laurent" wrote in message 
>> news:35aabdcd-6064-4999-9cdf-d143b0593a31 at googlegroups.com...
>>> On Wednesday, May 6, 2015 at 11:23:36 PM UTC+2, Randy Brukardt wrote:
>> ...
>>>>I'd prefer a completely different design for both of these packages, so we 
>>>>could add some
>>>>mechanism to allow direct conversions, but that's likely too radical.)
>>>
>>> Why would that be too radical?
>> 
>> Well, either we'd modify the existing packages (which would be very 
>> incompatible, so it would never happen), or we'd have to add new ones. In 
>> the later case, there would be a lot of opposition because we'd be 
>> duplicating functionality. If it happened, it would happen because of adding 
>> something like Root_String'Class to the language; then we'd need packages on 
>> that type and those would necessarily be new. But I'm not expecting much 
>> happening on that.
> 
> Question: Why couldn't we define new string packages and allow the old
> ones to be placed in [e.g.] Ada.Annex_J.[old-package] with perhaps
> allowing compilers to rename the Annex_J children within the library as
> the Strings-packages?

We could but since strings cannot be designed *reasonable* in existing Ada,
better leave it as is without introducing more mess than it is already
there.

For strings types hierarchy you need:

1. MD. Since there exist n-ary string operations, e.g. "&".

2. Non-tagged classes, since we don't want statically known strings and
slices having tags.

3. Properly designed indexing operations and abstract array interfaces.
Strings are arrays.

4. Proper MI, since strings must comprise several hierarchies, to reflect
encoding, memory management and other string aspects.

5. Constraint propagation that will remove discriminants and bounds from
statically constrained instances.

6. Parallel types hierarchies to handle convoluted hierarchies of string
types and hierarchies of character types.

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