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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Exception_Occurence and language designers
Date: Tue, 5 Dec 2017 21:48:36 +0100
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Xref: reader02.eternal-september.org comp.lang.ada:49387
Date: 2017-12-05T21:48:36+01:00
List-Id: <comp.lang.ada>

On 2017-12-05 21:05, G. B. wrote:
> Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
>> On 05/12/2017 01:16, G. B. wrote:
>>
>>> How about this: the idea of creating normal,
>>> typed objects as payload of wild jumps in
>>> abnormal (exceptional) situations is rather optimistic.
>>
>> The problem is upward closures. (...):
>>
>> This works in C++ because there all types are global.
> 
> Creating objects in exceptional situations,
> if meaningfully possible at all, will work in
> C++ as long as the programmer manages
> to copy the closure of data into the thrown
> object, IINM.

In Ada it necessarily becomes type closure. No way you could marry 
static typing with that.

>>   Root_Exception_Attachment (...)
>>
>> Apart from being not very useful and requiring a lot of overhead
> 
> If non-local jumps should pass information up the
> call chain, then why not ask for a mechanism that
> does just that?

Fine, if you manage to express that mechanism in terms of static strong 
typing, be my guest.

> Trying to load exceptions with this seems like misusing a concept.

Which is why Ada 95 didn't do that. Exception_Occurrence is a plain 
type, no magic.

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