On Wed, 2012-11-14 at 18:31 -0800, Andrei Alexandrescu wrote: > > array(map!"a.dup"(stdin.byLine()))
As it seems there is a good way of handling ranges with transient front for algorithms that need a persistent front? Why not simply document any transient range to be transient (should be anyway) and add the little hint to map. Also note that some algorithms might not work as expected with transient fronts. In addition, at least the algorithms in phobos should state in their documentation whether they rely on non transient front or not. To me it seems that ranges and algorithms already offer a solution to the problem. The other way round it would of course be better (safe behaviour the default, fast the option) but as a matter of fact there is no real unsafe behaviour, it just might be unexpected if you don't know what you are doing. On the other hand if an algorithm depends unnecessarily on non transient fronts it should be fixed. If there are many algorithms which can be more efficient with the dependency on non transient front, we could simply provide a second module, called std.transalgorithm (or something) offering dedicated algorithms for transient fronts. (So people don't have to role their own) I think this is a very clean and straight forward solution. If you want something that simply works you just use map!"a.dup" ( or whatever you need to copy your elements) and don't care. If you want performance then you would have to check what algorithms to use and have a look at std.transalgorithm. My apologies if someone else already suggested something like this, I haven't read all the threads about this topic entirely.
