Re: Building blocks (Was: Design By Contract)

[Stephen Leake <Stephen.Leake@gsfc.nasa.gov>]

Paul Johnson wrote:
> 
> Ada allows the programmer to quietly ignore an exception and pretend
> that a routine succeeded when in fact it failed.  This is wrong.

I assume you are talking about:
begin
   ... some code
exception 
when others => 
   null;
end;

which ignores exceptions. Usually, this is a bad idea. But sometimes, it 
is essential. Consider the top level loop of a fail-safe system:

loop
   begin
      Initialize;
      loop
         ... do main stuff
      end loop
   exception
   when others =>
      null;
   end;
end loop;

This way, no matter what the "main stuff" does, the outer loop will try
again
if an unhandled exception is raised. Exiting to the "environment" would
be less safe.

How does Eiffel handle this situation?

This is a general philosophy of Ada; provide the tools to do various
jobs. Don't force a programmer to do something because it's "good".
> 
> Paul.
> --------------------------------+---------------------------------
> Paul Johnson                    | You are lost in a maze of twisty
> Email: Paul@treetop.demon.co.uk | little standards, all different.
>        paul.johnson@gecm.com    |

-- 
- Stephe