On 2/22/11 3:23 PM, Philippe Sigaud wrote:
On Tue, Feb 22, 2011 at 15:23, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> wrote:
auto singletonRange(T)(T element)
{
static struct Result
{
private T _element;
private bool _done;
@property bool empty() { return _done; }
@property auto front() { assert(!empty); return _element; }
void popFront() { assert(!empty); _done = true; }
auto save() { return this; }
}
return Result(element, false);
}
That's also what many people would like a findFirst function to
return. Either a 1-element range with the found value or an empty
range if the value doesn't exist.
auto v = findFirst(range, needle);
if (!v.empty) { ... }
Good point.
Maybe you could allow for the creation of an empty output
singletonRange where a lone value could then be put.
auto singleton(T)() { ... } but the user would need to provide the 'T'
by himself.
Yah, I thought of that after posting. It would look something like this:
auto singletonRange(T)()
{
typeof(singletonRange(T.init)) result = void;
result._done = true;
return result;
}
No mercy :o). But that's unsafe so probably we'd need to leave out "= void".
and then:
void put(T element) {assert(empty); _element = element;}
That could be a way to modify a container. Btw, is there a way to have
an empty container and use an output range to fill it? I didn't look
at std.container for quite some time.
No, but this may be an interesting idea to pursue.
Andrei
