Re: [Boost-users] size_type doubts / integer library..

From: Zeljko Vrba (zvrba_at_[hidden])
Date: 2008-08-19 06:49:03

On Tue, Aug 19, 2008 at 11:02:44AM +0300, dizzy wrote:
>
> to be solved than the additional compare operation). If I were to decide how 
> to do it I would have decided as you suggested since it seems the least error 
> prone for the user. I'm sure however that there were other reasons that made 
>
Hooray, we have agreed on at least something! :-)

> 
> And since a ctor used for conversion is such a user declared ctor then you 
> can't have it POD anymore. Either if you don't want implicit conversion with a 
> ctor you still need your own ctors taking integer values or other integer 
> types (with other ranges) and that makes it not a POD anymore right?
> 
You're right, I want constructors.  I have yet to see a case where a
user-defined constructor alters the layout of what an otherwise would be a
POD-class, but..

> 
> Yes it would have been nice to know portably an arithmetic operation has 
> overflowed that results in fast CPU code checking for some flag. But I am not 
> sure if this is possible for all CPUs that C++ is supposed to run on or how 
> useful would be.
> 
Such facility can be implemented in software, if hardware does not provide a
better way.  Efficiency of implementation has nothing to say about it -- not
even all CPUs support floating-point in hardware, yet FP is standardized.  If
you would use a construct like overflows(a+b), you'd pay the price, however
large/small it might be, otherwise you wouldn't.

Anyway, time to bring this discussion towards the end -- it seems that we
don't have a large gap in opinions, after all.