Re: [Caml-list] OO design

[David Teller <David.Teller@ens-lyon.org>]

On Monday 08 May 2006 05:17, Jacques Garrigue wrote:
> I would be tempted to say: there is no answer.
> Ocaml objects are not about enforcing protocols, but about allowing
> inheritance and structural subtyping, and this does not fit well with
> your problem.

Which brings us to a question : how do you enforce protocols in OCaml ?

Say, is there a "good" way of rewriting file-related operations so that, say, 
ProtocolUnix.read and ProtocolUnix.write *statically* only accept opened 
files, and in addition, ProtocolUnix.write only accepts files which have been 
opened with write priviledges ?

I mean, there are manners of checking this with, say, model checking tools. In 
the specific case of file management, I guess we can do it with a little bit 
of simple subclassing, but I assume there's a large run-time penalty for this 
extra bit of checking, due to the management of objects by OCaml. Has anyone 
attempted to determine how well this scales up ? Or explored other options ?

Cheers,
 David