[boost] Re: mpl::inherit_linearly reuse to produce loki's tuple?

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
http://www.boost-consulting.com