Re: random numbers in bulk

[Marc Glisse <marc dot glisse at inria dot fr>]

On Sat, 25 Aug 2012, Ulrich Drepper wrote:

> On Sat, Aug 25, 2012 at 8:29 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
> > Understood, but you do *not* loose performance by having those fill functions templates,
>
> Let's see.  The prototypes will then be something like this:
>
>  template<typename _RealType = double>
>    class normal_distribution
>    {
>
>      template<typename _UniformRandomNumberGenerator,
> 	       typename _OutputIterator>
> 	void
> 	fill(_OutputIterator __f, _OutputIterator __t,
> 	     _UniformRandomNumberGenerator& __urng,
> 	     const param_type& __p);
>    };

The std::generate(_n) function seems closer than std::fill. Not sure if 
overloading that function (std::generate_n) would make sense, it avoids 
changing the interface.

> Now I want to define a specialized function which works for a double
> iterator and all RNGs.  That's not possible because it means partial
> specialization.
>
> Therefore I'd have to add another member function to the class.  If
> this is what is wanted I can do this (in fact, I have the code ready).
> It just looks worse because the special functions are in some cases
> architecture-specific.  This means the code will be littered with
> arch-specific code.

If the goal is to avoid listing several overloads in the class, it is 
still possible to dispatch in the (out-of-class) definition of fill. Or is 
the goal to make it extensible, in the sense that a user can still add 
"specializations" (whatever the technical means used, which don't have to 
be what C++ calls specialization)?

--
Marc Glisse