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

From: Zeljko Vrba (zvrba_at_[hidden])
Date: 2008-08-18 11:29:27

On Mon, Aug 18, 2008 at 06:03:11PM +0300, dizzy wrote:
> >
> > It can work perfectly, there are only two cases:
> >   - a < 0 : true, done, no need for conversion
> >   - a >= 0 : ordinary unsigned comparison
> 
> Well that still is a too much cost for some people. You just transformed a 
> single CPU comparison of a < b to 2 comparison instructions. People who made 
> sure that "a" is always positive in their program do not want to pay for the 
> price of doing one more comparison for those who didn't.
> 
Well, then they get to cast their signed number to unsigned: (unsigned)a < b,
problem solved.

> 
> Depends how do you define security, when you receive a reference are you 
>
Being able to detect invalid input.  malloc(-12) is certainly meaningless,
malloc(something_large), might be, might be not - where's the border? 

>
> references? I hope not! And if not, then why do you trust references but do 
> not trust other syntactic sugar like "unsigned"? Because I meant of using it 
>
It's not about trust - it's about being unable to detect invalid input.

> 
> So you make your new Integer class a POD. But then how do you enable implicit 
> conversions (for most of the operator overloads sure you can overload them 
> non-member).
> 
PODs can have member functions, at least if I interpret this correctly:
http://www.fnal.gov/docs/working-groups/fpcltf/Pkg/ISOcxx/doc/POD.html

> 
> That's how CPUs were made, they don't make much sense in strict mathematical 
> arithmetic but they make a lot of sense in binary mode arithmetic.
> 
CPUs provide various simple means to detect anomalous conditions.  C++ does not.

> 
> Sure it can, the new Integer type you are doing is such an option. Where 
> should the line be drawn between whatever other high level language features 
> some users need and what the standard library provides?
> 
If there's place for locale...