Any libunwind experts n da house?

[Andrei Alexandrescu via Digitalmars-d]

On 9/24/14, 5:12 AM, Iain Buclaw via Digitalmars-d wrote:
> On 24 September 2014 12:27, IgorStepanov via Digitalmars-d
> <digitalmars-d at puremagic.com> wrote:
>> On Tuesday, 23 September 2014 at 17:37:42 UTC, Andrei Alexandrescu wrote:
>>>
>>> We need a libunwind expert to figure out a good approach for handling
>>> exceptions thrown by C++ code into D.
>>>
>>> Is anyone fluent with libunwind?
>>>
>>>
>>> Andrei
>>
>>
>> Is there plans to catching C++ exceptions in D?
>
> I'd say no to such an idea.

I understand the difficulty of it. However, we should look into it 
closely. Preventing D code from catching C++ exceptions forces one to 
implement the driver/event loop/etc in C++, which is quite unpleasant. 
It essentially takes C++ compatibility a few good notches down.

>> What kind of C++ exceptions planned to catch in D?
>
> None

I wonder how difficult would be to create a wrapper class CppException 
for everything derived from C++ std::exception. It would not save the 
exact exception, but it would save its what() string and perhaps the 
typeid().name(). A translator would create CppException objects from 
std::exception objects and their derivatives.

How hard would that be? Please advise.

>> For example C++ can throw primitive types exceptions, for example int.
>> Of cource, them can be wrapped into special D CPPException : Throwable,
>> class, which contains string representation of C++ exception.
>> What about C++ polymorthic exceptions? AFAIK, C++ exception are throwing
>> by-value, and catching by ref (to allow polimorthic catch). Where C++ calls
>> destructor for exception? In catch block? In D GC handles an exception
>> lifetime.
>> Is there any ideas about it?
>> P.S. I tell about user-side of catching C++ exceptions, not about
>> implementation.
>
> Let C++ land catch the exception and deal with it.

Believe me, I hear you :o). I'm afraid we need to do something better 
about it.


Andrei