Re: Signature Package With Generic Proceedure

[Keean Schupke <keean.schupke@googlemail.com>]

On Tuesday, 24 July 2012 09:43:03 UTC+1, Dmitry A. Kazakov  wrote:
> On Tue, 24 Jul 2012 01:02:55 -0700 (PDT), Keean Schupke wrote:
> 
> > On Tuesday, 24 July 2012 03:53:20 UTC+1, Randy Brukardt  wrote:
> >> "Keean Schupke" wrote in message 
> >> ...
> >> > This is datatype generic programming, one of the things I thought Ada is 
> >> > good at.
> >> > Signatures are the only way in Ada of doing this with no runtime cost, and 
> >> > the only way
> >> > using generics. Signatures belong to a family of constructs across several 
> >> > languages with
> >> > similar properties. For example:
> >> 
> >> There's nothing in Ada that says generics have to be implemented with "no 
> >> runtime cost". Many Ada 83 implementations, and a few more recent 
> >> implementations, share all generic instantiations. The effect is very 
> >> similar to tagged type dispatching, and it's most useful when there are a 
> >> lot of instances in a program. Janus/Ada certainly does this (it might be 
> >> the last to do "universal generic sharing"). Some Ada implementations do 
> >> "partial generic sharing", where the parameters involved determine if 
> >> sharing is used.
> >> 
> >> Normally, at this point, I'd say something about premature optimization, but 
> >> I realize from your past messages that you're already beyond that stage, so 
> >> I won't say any more.
> > 
> > Using DG is a choice like using OO.
> 
> DG is "dangerous goods" or "differential geometry"?
> 
> > Languages seem to be very keen to add features to support OO programming.
> > The zero run time cost is 'potential' because all types can be statically
> > determined at compile time. GNAT does this (maybe because it shares a
> > backend with C++)
> 
> GNAT does this because in Ada static dispatch is always zero run-time cost.
> This gives full advantages of OO over generics with no performance loss.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de

DG is Datatype Generic programming, its a different way of working to Object Oriented design, focusing on algorithms and concepts (or type-classes or signature packages). It has many advantages over OO with potentially better performance.

Cheers,
Keean.