Re: Seeking for papers about tagged types vs access to subprograms

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Tue, 30 Apr 2013 02:41:35 +0200, Shark8 <onewingedshark@gmail.com> a  
écrit:

> On Monday, April 29, 2013 6:31:37 PM UTC-6, Hibou57 (Yannick Duchêne)  
> wrote:
>>
>> Same question in the context of `Ada.Finalization`. Similar semantic  
>> could
>> have been made available without requiring tagged types.
>
> This is true; but it's likely that tagged-types were the easiest method  
> to implement it.

I don't know if this was the easiest, but I personally feel this may be  
was the option offering the biggest use‑case coverage.

I though relying on tagged type allowed to be the most general as  
possible. Defining an `Ada.Finalization` applicable to tagged types,  
obviously requires tagged types. On the other hand, as what's not using  
tagged type, may be redefined with little modification, to use tagged  
types, using tagged types was the best option to cover the most general  
case, even the ones not using tagged types in the first place.

However, tagged types may be excluded (ex. if there are proof  
requirements) or not available (ex. the runtime in use does not support  
it). That's a bit a pity to not be able to use something like  
`Ada.Finalization` for applications not using tagged types. I even believe  
`Ada.Finalization` is harder to avoid than tagged types  
(`Ada.Finalization` looks more fundamental to me), especially that it  
comes with added safety (as much as strong typing and ability to return  
unconstrained types are).


-- 
“Syntactic sugar causes cancer of the semi-colons.” [1]
“Structured Programming supports the law of the excluded muddle.” [1]
[1]: Epigrams on Programming — Alan J. — P. Yale University