scope + destructor with Exception parameter for RAII

[Sean Kelly]

Leandro Lucarella wrote:
> Sean Kelly escribió:
>>> I don't see why writing correct code is that complicated. And how do 
>>> you address the problem of repeating error handling code and the lack 
>>> of encapsulation of scope(success/failure)?
>>
>> The lack of encapsulation doesn't bother me much, though now I see 
>> what you're getting at.  I do think that having:
>>
>>     auto scope t = new Transaction();
>>     scope(failure) t.rollback();
>>     // commits if not rolled back on scope exit, alternately use
>>     scope(success) t.commit();
>>
>> actually aids readability a bit, at the expense of some extra code.
> 
> So you are against all RAII done in the C++ way, I guess...

Not at all, I use it all the time :-)  But I don't think the C++ method 
works well for situations like the above.  Andrei's original series of 
articles on scope guards actually used transactions as their primary 
example for when the C++ method falls apart, and I agree with his 
reasoning.  That said, part of his argument *was* because the C++ method 
for detecting in-flight exceptions isn't very reliable.  Providing a 
fixed version in D would allow for both methods to be used--it's just a 
matter of making the necessary changes.  All of which could be done in 
phobos/internal, by the way.


Sean