Re: [boost] iterator_adaptors.hpp/transform_iterator

From: David Abrahams (abrahams_at_[hidden])
Date: 2001-03-28 11:16:59

----- Original Message -----
From: "Gary Powell" <Gary.Powell_at_[hidden]>

> I understand your current reasoning, but for VTL to work well, I really
> could use the extended iterator concepts that Jeremy wrote about.

I understand. Work like Jeremy's extended iterator concepts is really only
going to be valuable (and proven!) in the context of a library that needs
it. Therefore, I suggest you pick it up and try to use it for VTL.

> Until
> then, I can test the result type of the function and select the correct
> Iterator adaptor

If you can figure that out, maybe you can also figure out how to unify the
Transform and Projection iterator adaptors so we don't need two separate
adaptors?

> , but its going to bug people that for a transform on a
> random access container, they can only do forward access.

Actually, I probably should clarify again: if the underlying iterator
supports random access, the transform-adapted iterator will support it, too.
It just won't be a RandomAccessIterator, because the reference type will be
wrong. Since the reference type is wrong, for RandomAccessIterator, the
iterator_category will be just input_iterator_tag.

> It makes no sense to link these two concepts.

Yeah, it would've been nice if Stepanov had 20-20 foresight, eh? He did
remarkably well, all things considered.

> Again I thank you both for all your work on this.

You're welcome!

-Dave