"Andrei Alexandrescu" wrote > Steven Schveighoffer wrote: >> While we're on the subject of ditching, can we get rid of >> foreach_reverse? How hard is it for a range to just have a reverse >> property: >> >> foreach(element; myrange.reverse) >> >> Which simply reverses the order of traversal? That also would moot the >> toe/last/tail/etc. debate ;) > > I wish that debate went away. But eliminating toe and retreat would > require requiring .reverse as a primitive for *all* ranges, which is > wasteful and repetitive. Instead, a better design is to have ranges (those > that can) offer toe and retreat primitives such that a generic function > retro offers backward iteration for any range. In addition, certain > algorithms (such as the one that reverses a range in place) need to > manipulate the same range from two ends. Implementing them using .reverse > and a second range would be more difficult.
I didn't say you couldn't provide toe and retreat in Phobos' ranges (for the reverse-a-range function). Most likely such an algorithm is not using foreach and foreach_reverse, but using the functions directly. My point was, foreach_reverse is an eyesore and a hack, and there really is no need for it. And what a perfect time to get rid of it, since we are already changing how foreach works ;) I realize that this wouldn't really kill the toe debate for Phobos, but at least it would be a library decision, and not part of the compiler. -Steve
