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

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

Le Mon, 06 May 2013 20:55:34 +0200, Dmitry A. Kazakov  
<mailbox@dmitry-kazakov.de> a écrit:
>
> Instead of banishing exceptions one should put contracts on them.
>

In the meanwhile, that's hard to have exception contract without breaking  
separation of implementation and specification; or else, the specification  
would have to express requirements on the implementation, which is not a  
so bad idea on its own, but which is something foreign to Ada, except as  
comments.

However, there is an big‑picture contract on exceptions which would be  
simple an useful without breaking privacy of implementation: a sub‑program  
may or may not raise synchronous exceptions. This contract would be enough  
I believe, especially with the help of the (non‑standard) pragma  
`No_Exception_Propagation`.

Asynchronous exceptions, such as hardware error, memory chip error, OS  
error, and so on, would be left uncovered. Anyway, I see nothing else if  
not a rather immediate program termination when it occurs (may be just  
logging a short static message, and then terminate).

-- 
“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