on Thu Oct 06 2011, "Phil Endecott" <spam_from_boost_dev-AT-chezphil.org> wrote:
Dave Abrahams wrote:
on Thu Oct 06 2011, "Phil Endecott" <spam_from_boost_dev-AT-chezphil.org> wrote:
Dave Abrahams wrote:
I'd like to see somebody write the description of the algorithm, including the concept requirements.
Well we can start by copying what the experts wrote for std::find, can't we?
Who are "the experts?" The specification that we have in the standard library is not current best practice when it comes to Generic Programming. I'm not sure who crafted the language, but it's not what we should do today.
Well perhaps we need to step back and decide what we're trying to do here. Are we trying to create stuff that is so "best practice" that it's even better than the not-yet-ratified new version of the language?
I guess you missed the news. C++11 is ratified. But, yeah, why shouldn't we do better if we can?
Are we making that requirement an absolute one that trumps useful functionality? If so, why? It seems unnecessarily puritan to me.
Just to be completely honest here: I've been wondering the same thing... maybe I've been poisoned by Stepanovian purity.
For the non-predicate version it just says "Returns: The first iterator i in the range [first,last) for which *i==value holds" (n3242).
Exactly, a pile of syntax.
Back in the "clamp" discussion, I tried to argue that for trivial operations I would actually prefer to have a "pile of syntax" rather than a free-standing spec.
It's an interesting idea that trivial things are better described in terms of their implementations. *Very* interesting.
My argument was that for trivial things we actually have the implementation in our minds first and then find ourselves trying to think of some other way of expressing the same thing in order to write down a spec; in the process, we're as likely to make a mistake in the spec as we are to make a mistake in the implementation. Examples:
clamp(val,lo,hi) = val<lo ? lo : val>hi : hi : val;
vs.
clamp(val,lo,hi) returns the middle value when (val,lo,hi) are ordered according to operator<
Wow, that certainly is stark. When I try to describe it better in words, it reads just like your implementation. But I'm not sure what that proves. Swap is a trivial algorithm. Isn't it best described as "exchanges the values of its arguments?" -- Dave Abrahams BoostPro Computing http://www.boostpro.com