Arno, On Tue, Sep 2, 2008 at 4:38 PM, Arno Schödl <aschoedl@think-cell.com> wrote:
The RangeEx documentation writes something like "what algorithms are to containers, adaptor ranges are to ranges". Whenever you are applying one (non-permutating) algorithm to a container, and then another and then another, you can stack range adaptors. It's like lazy evaluation of a Haskell list.
Sheesh; give me a little credit, please. I know what range adaptors do.
So why are you asking these questions then? With smart compilers, generic programming is supposed to produce code that is pretty close to handcrafted code. That is what people expect, and that is what generic programming is sold on. The current range adaptors were far from it. And even if stacks don't exceed size 3 or 4 in practice, which is all I have in my code, why produce code that is factor 8 or 16 slower or more storage-bloated than necessary? As we have seen, the reason was not that the problem is intractable with generic programming. It just took a little thought to do it right.
Please do not get frustrated. We all want to improve Range / RangeEx. I have to apologise for not offering to modify the code sooner. I have been watching, and learning. Once I have understood the design alternatives and have fully comprehended the optimum solution I will implement the suggested improvements. It looks like I will need to coordinate with the Iterator library developers for the optimum solution. So far RangeEx has not made it into Boost, and thus asking for changes in other libraries before seemed unlikely to succeed. While I accept that the adaptors are possibly not the optimum solution they are at least implementations of the functionality. I would gladly accept superior contributions ;-). I am also happy to spend more time improving them myself. I have to apologise for slow response times, my full-time job simply doesn't allow me enough time to contribute to this discussion as much as I probably ought to. You have made some very valid technical points, let's focus on these please.
-- Dr. Arno Schoedl · aschoedl@think-cell.com Technical Director
Best wishes, Neil Groves