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From: David Abrahams (dave_at_[hidden])
Date: 2004-12-14 16:05:44

Larry Evans wrote:
> Thanks for your responses, David.

Sure thing.

> >>However, in addition, if variant (i.e. sum) is thrown onto the
> >>scales, then I believe easier undestanding wins.
> > Maybe you're not the best judge of easy understanding.
> I completely agree.

You snipped the context. My point was that you managed to confuse me by
talking about stuff like sum and product without any introduction to
what they were.

> I believe it's pretty typical that the coder
> initially believes his code is easier to understand than reviewers
> would say.
> However, I'd guess that one attempting to understand product would
> simply look at the project<Index> code, then at the factor<,, Index>
> superclass
> to find my_field of type TypeMap<Index>::type and
> understand product.

???? You're off in some other dimension again. Did I miss all this from
an earlier post ????

What is product, project, factor, my_field, and what language is

  factor<,, Index>


> OTOH, as reflected in my previous response
> terminated with :( , understanding how tuple accessed the selected
> fields seemed much harder, at least to me. Maybe you could give a
> brief description of the thought process you went through in
> understanding product.

I didn't. I have no clue what you're talking about.

> > What does variant have to do with sum? It's completely non-obvious
> > to me.
> Well, maybe that's part of the problem. Are you assuming sum has
> something to do with numbers. I'd meant it to mean disjoint sum
> applied to types, and of course variant does model disjoint sum. Is
> that the reason for the disconnect (of our mutual understanding) ?

Maybe. You do seem to be assuming all kinds of background vocabulary I
don't have.

> >
> >
> >>In addition, I think sum can be modified by adding:
> >>
> >> term<...Index>::accept(visitor&a_viz)
> >> {
> >> if(index() == Index)
> >> { a_viz(mpl::int_c<Index>(), project<Index>());}
> >> else
> >> { term<...,Index-1>::accept(a_viz);}
> >> }
> >>
> >>which is essentially the visitor pattern.
> >
> >
> > You've lost me completely.
> Well, I had assumed you'd looked at sum.hpp

What sum.hpp??

Dave Abrahams
Boost Consulting

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