On Mon, Mar 2, 2009 at 10:19 AM, Arno Schödl <aschoedl@think-cell.com>wrote:
In this latter case, I don't see how you can do without an in-place algorithm, which IMO should be named differently. Or is the idea to do this:
vector<int> vecn; vecn=transformed( vecn, func ); // overwriting the range that the adaptor is still working on? sort( vecn ); // sort cannot be done lazily
I don't feel comfortable with it. Some adaptors are o.k. with it (transform), while others (say, duplicate each element) are not. For some (slice), it will depend on the implementation of operator=. And the compiler won't warn you.
AFAICS there's no issue in principle with something like vecn | boost::adaptors::sort as an expression. This would result in a range that could be iterated through lazily, although in total could not be as efficient as a traditional sort. Naturally the underlying range must not change in any way, or all bets are off. Regards, Rob.