On Sunday, 22 November 2015 at 00:31:53 UTC, Jonathan M Davis
wrote:
Honestly, arrays suck as output ranges. They don't get appended
to; they get filled, and for better or worse, the documentation
for copy is probably assuming that you know that. If you want
your array to be appended to when using it as an output range,
then you need to use std.array.Appender.
Hi Jonathan, thanks for the reply and the info about
std.array.Appender. I was actually using copy to fill an array,
not append. However, I also wanted to preallocate the space. And,
since I'm mainly trying to understand the language, I was also
trying to figure out the difference between these two forms of
creating a dynamic array with an initial size:
auto x = new int[](n);
int[] y; y.reserve(n);
The obvious difference is that first initializes n values, the
second form does not. I'm still unclear if there are other
material differences, or when one might be preferred over the
other :) It's was in this context the behavior of copy surprised
me, that it wouldn't operate on the second form without first
filling in the elements. If this seems unclear, I can provide a
slightly longer sample showing what I was doing.
--Jon
