Re: Ada design bug or GNAT bug?

["Randy Brukardt" <randy@rrsoftware.com>]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 1436 bytes --]

"Björn Lundin" <b.f.lundin@gmail.com> wrote in message 
news:mn8hok$fdf$1@dont-email.me...
> On 2015-07-04 09:46, Simon Wright wrote:
>> Shark8 <onewingedshark@gmail.com> writes:
>>
>>> Also, I seem to recall your dislike of INTERFACEs -- in hindsight,
>>> what would you have done differently if you needed the mechanism of
>>> "Type T has functions X, Y, and X" applied to a group of types?
>>> Generics, or some variations thereof?
>>
>> Generic signature packages?
>>
>
> I had this problem when implementing another companies proprietary
> communications protocol, that we needed to communicate with.
> The physical devices were picking-robots.
> All messages had a common headers and then message specific fields.
> And they had to have certain functions. To_String, Save_to_Database,
> Send, etc.
>
> Since I had complete control over the implementation, I
> ended up using inheritance from an abstract type.
>
> Some functions of the abstract type were implemented,
> and others - to specialized for the inherited type -
> was declared abstract.

Right, with single inheritance. Good enough for 98% of problems, IMHO. I've 
used abstract types this way (in Claw and in Claw tools), but I found that 
the main gain was the shared implementations that could be provided by the 
abstract type. Interfaces don't allow them, so they provide cool-looking, 
but mainly useless capabilities.

                                 Randy.