Re: foreach on interval index by ref increment

[Marco Leise]

Am 22.01.2012, 04:38 Uhr, schrieb bearophile <bearophileh...@lycos.com>:
Regarding this code:


import core.stdc.stdio;
void main() {
    foreach (ref i; 0 .. 10) {
        printf("i = %d\n", i);
        i++;
    }
}


He says it "works as expected":

i = 0
i = 2
i = 4
i = 6
i = 8

[...]

Skipping to the next number to me looks like "i++" is doing something  
more like a pointer increment. It's ugly, and looks bug prone. foreach  
is not a light syntax sugar over a for loop, it's a bit different. I  
have discussed a similar topic some time ago.

Actually it is light syntax sugar over a for loop. The compiler sometimes  
prints out the syntax tree. But I have to agree that this use of ref  
doesn't look kosher. If I had my little way, I would adapt the ideas from  
VB, where you would write the above loop as "for i=0 to 9 step 2". So in D:

        foreach (i; 0 ... 9, +2)

also nice would be:

        foreach (i; 9 ... 0)

The alternative:

        foreach_reverse(i; 0 .. 10)

is really hard on the human brain :D