Help with Ranges
charles at email.sometld
Mon Jul 27 17:10:44 UTC 2020
On Sunday, 26 July 2020 at 14:56:35 UTC, Steven Schveighoffer
> A map that returns an lvalue would be sortable, but you would
> be sorting the processed elements, and probably not the
> original elements.
Indeed, but that's what I want: sort the process elements.
Otherwise, I'd place sort before the transformations.
> I have found this handy tool quite useful in my code where I
> need a temporary array:
> // creates a concrete range (std.container.array.Array range)
> out of the
> // original range that is eagerly fetched, and then can be
> processed, without
> // allocating extra garbage on the heap.
> auto concreteRange(Range)(Range r)
> import std.range : ElementType;
> import std.container.array : Array;
> return Array!(ElementType!Range)(r);
> Slicing an Array will keep the reference count correctly, and
> destroy the memory automatically after you're done using it. So
> it's perfect for temporary arrays in pipelining.
This works well, and it's rather nifty. Still, I'm confused
since, as far as I know, map wraps its source, i.e. the array in
this case, which is sortable. It seems to me the only reason I
can't sort MapResult is because it doesn't have the proper
I'm obviously missing something.
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