Re: Forcing Exception Handling

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Tue, 1 Mar 2011 18:00:32 -0600, Randy Brukardt wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
> news:3es12u7g6ppm.4lk5iya2a586.dlg@40tude.net...
>> On Mon, 28 Feb 2011 21:54:08 -0600, Randy Brukardt wrote:
> ...
>>> That seems like bad software management to
>>> me. In any case, any such "contracts" in Ada would have to be optional 
>>> (for
>>> compatibility reasons), and that might actually help reduce the problems.
>>
>> Unless Storage_Error and Program_Error made manageable contracted
>> exceptions would have only limited use.
> 
> I agree; I think that if we go this way all exceptions would have to appear 
> in the contract. To make that managable, we'd also need a way to define a 
> "set" of exceptions so they could be referred to together. I personally 
> think that is sufficient, and it would let the compiler tell you what it 
> knows about exceptions being raised.

I thought about sort of conditional exceptions. E.g. storage error possibly
raised when stack has less than n storage units. The compiler should
estimate n in the cases mandated by the ARM. In other cases (recursion etc)
the program is illegal, but the programmer may specify n explicitly using a
pragma (he must know what he's doing, of course).

Another example of conditional exception would be "I don't raise, if you
don't."

And we need a mechanism of exception propagation from slave tasks to their
masters (when the task's exception contract is not null).

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de