On Wednesday, 14 May 2014 at 11:13:10 UTC, John Colvin wrote:
On Wednesday, 14 May 2014 at 09:38:10 UTC, Chris wrote:
I have code that uses the following:
string[][size_t] myArray;
1. myArray = [0:["t", "o", "m"], 1:["s", "m", "i", "th"]];
However, I've found out that I never need an assoc array and a
"linear" array would be just fine, as in
2. myArray = [["t", "o", "m"], ["s", "m", "i", "th"]];
Is there any huge difference as regards performance and memory
footprint between the two? Or is 2. basically 1. under the
hood?
If you don't need the features of associative arrays, don't use
them.
Normal arrays are much simpler, faster and (due to some
outstanding problems with associative arrays in D) less
bug-prone. Associative arrays, by definition, require a lot
more work behind the scenes for both reading and writing.
The question is, if they are _much_ faster. With this type
(string[][size_t]) I haven't encountered any bugs yet. On the
other hand, it introduces some rather stilted logic sometimes, as
in
foreach (size_t i; 0..myArray.length) {
// do something with myArray[i];
}
because it's not sorted. This, or I sort it first. Anyway,
there's always an overhead associated with associative arrays.
I'll have to see how big this breaking change would be, and
decide, if it's worth it.
Profiling is not really feasible, because for this to work
properly, I would have to introduce the change first to be able
to compare both. Nothing worse than carefully changing things
only to find out, it doesn't really speed up things.
