Re: [boost] Bounded types

From: Jeff Garland (jeff_at_[hidden])
Date: 2005-10-23 21:48:08

On Thu, 20 Oct 2005 23:09:58 +0200, Robert Kawulak wrote
> Hi, 
> 
> > From: Neal Becker
> <...>
> > I'm more
> > interested in bound specified at runtime.  I believe (without 
> > proof) that
> > for many applications there will be little performance 
> > difference.  I say
> > this because I'm expecting in many (most?) cases the actual 
> > integral values
> > will be known to the compiler.
> > 
> > Has any thought been given to adding this?  Or, perhaps even 
> > making this the
> > default bounded_int, (wrapping_int, etc.) type?
> 
> Yes, I'm still thinking about this. The difference between static and
> run-time bounds is that in the latter case a bounded object needs to 
> store the bounds which makes its size at least 3 times bigger. 
> Another one is that with static bounds many checking operations may 
> be optimised-away or at least inlined. Therefore I'd rather not make 
> run-time bounds the default. I'm working on this as an optional 
> feature, but this is a little bit harder than it seems to unite the 
> two concepts.

Catching up with really old email...

I'll just say that for my money I *only* care about compile time types. The
extra storage Robert cites for an application like date-time is unacceptable.
 I'll also state that I believe there will be a performance hit as well on
construction of the type (probably 3 integer copies instead of 1 in the
constructor). 

I'll try to find some time to look over the latest implementation soon....

Jeff