Re: More on "Component Programming"

[Andrei Alexandrescu]

On 5/27/13 5:36 PM, bearophile wrote:
This simple example shows the difference:
import std.stdio, std.algorithm;
void main() {
auto data = [1, 2, 3, 4];
foreach (xy; cartesianProduct(data, data))
writeln(xy);
}


Generates the tuples:
(1, 1)
(2, 1)
(3, 1)
(4, 1)
(1, 2)
(2, 2)
(3, 2)
(4, 2)
(1, 3)
(2, 3)
(3, 3)
(4, 3)
(1, 4)
(2, 4)
(3, 4)
(4, 4)

I'm disappointed cartesianProduct works that way; I should have caught 
that during the code review. A better iteration order would have spanned 
the lower position in both ranges first, i.e. create squares of 
increasing side in the 2D space.

Andrei