Boost logo

Boost :

From: David Abrahams (dave_at_[hidden])
Date: 2004-02-12 18:22:46

"David Bergman" <davidb_at_[hidden]> writes:

> David (Abrahams),
> First of all, I am excited that your proposal has been formally excepted
> into the TR, since the dichotomy of yours is the way to go. The reason for
> me to stay at the naming of things is to make you understand that there is a
> slight possibility of even quite skilled individuals being led astray by the
> terminology; as to perhaps clarify certain notions in forthcoming revisions.


> Since the old treatment of iterators dealt with only one dimension, they
> used the word "category." No need to be more specific "back then..."
> It is a bit confusing if we, in this new two-dimensional iterative
> world, use "category" *both* for the combined (intersected)
> concepts, being analogous to the old concepts, *and* for one of the
> dimensions. In our case, Traversal.

We are not ever doing that, AFAIK. "Category" never refers to
"Traversal" and always refers to old-style concepts/tags. If you know
of a place in the text where that happens, please point to it.

> We have to make the meta programming facilities, such as the tags
> used, be backward-compatible, with that I agree. So, we have to keep
> the "category tag" and "iterator category" and map them to something
> sensible.
> We just have to live with the categories, as realized by category
> tags, dealing *both* with unique combinations of the two orthogonal
> issues (backward compatibility etc.) *and* with only one of the
> issues, Traversal, I assume.

Now I'm lost again.

> Could one not make that clear, such as:
> "category tags can dispatch

Tags don't dispatch, and I consider that phrase extremely confusing,
and possibly misleading.

> based on both traversal capability and the combined capabilities of
> traversal and access"

Besides that, I have no clue about the intended meaning of the above
statement, so I wouldn't make it in an effort to clarify anything.

> I understand, and always understood, your proposal, which is very
> welcome, but I do also understand if others might find the
> mentioning of "category" a bit misleading, since we have the old,
> combined world, and the new dichotomy to deal with.

I still don't understand what you consider misleading. Please point
to a sentence and describe how it can be misread.

> And... one does, unfortunately, use the word "category" in generic
> programming for both a single concept and a family of related
> concepts,

I've never heard that before, and I'm pretty well-versed in GP. If
you could point me to an example in the literature, I'd be indebted.

> often including refinement hierarchies :-| I prefer the less charged word
> "set of concepts" that you used.

I appreciate that you're only trying to be helpful, but I really
can't understand you. Trying to figure out what you mean takes a lot
of time. If you won't take this suggestion,

  Quote some text from the paper, say "I think it should say
  ________" instead, and then say why you think so.

I don't think I'm going to spend much more time trying to figure out
what you want.


Dave Abrahams
Boost Consulting

Boost list run by bdawes at, gregod at, cpdaniel at, john at