Ranges of char and wchar

[via Digitalmars-d]

On Thursday, 8 May 2014 at 21:38:12 UTC, Andrei Alexandrescu
wrote:
> int fun(int[] a)
> {
>    auto before = format("Before: %s", a);
>    foreach (ref e; a) ++e;
>    auto after = format("After: %s", a);
>    writeln(before, "\n--->\n", after);
> }
>
> *ouch*

You might think that's bad, but there's nothing in that example
that is specific to formatting; that kind of behavior can happen
with any lazy range taking input by ref. (I guess that's one
drawback of providing functional programming without
immutability?) To be clear, I'm not saying that the idea was to
make the existing format function lazy, break existing code and
surprise people with that change in semantics. format() can be an
eager wrapper for the new lazy functionality. And
eagerness/laziness should be part of the specification IMO, even
more than asymptotic complexity should be part of the STL spec,
since (bug > performance bug).