Joel de Guzman wrote:
But it might be not: the question of what the result of to_upper(to_lower(to_upper(rng))) is supposed to be is not trivial at all.
The result will be a view. Then, if it's done correctly, ideally, the view transformations can collapse the view. IOTW, this:
to_lower_view<to_upper_view<range> >
will be optimized to:
to_lower_view<range>
Hmm, I'm not convinced of that. some_container tmp(to_upper_view(rng)); to_lower_view(tmp); would return something different than to_lower_view(to_upper_view(rng)) in languages which do not have a homomorphous characterwise mapping between lowercase and uppercase spelling (e.g. german: ß -> SS, but S -> s). For the same reason, a locale-aware to_upper_view would not be as trivial as one would think at first. (Not overly complex, either, probably). The collapsing views would produce a better quality output in the case of ß, but I'm not sure the behaviour of compiletime composition should differ from the behaviour of the runtime composition. Regards, m Send instant messages to your online friends http://au.messenger.yahoo.com