If you have an array of structs that is primarily accessed by columns (the same member in each item) rather than by rows (all members in a given item) it can be faster to store the members each in there own array. The Columns template automates this for POD struct types.

http://www.dsource.org/projects/scrapple/browser/trunk/columns/columns.d

On Saturday, 13 December 2008 at 21:13:52 UTC, BCS wrote:
> If you have an array of structs that is primarily accessed by columns (the same member in each item) rather than by rows (all members in a given item) it can be faster to store the members each in there own array. The Columns template automates this for POD struct types.
>
> http://www.dsource.org/projects/scrapple/browser/trunk/columns/columns.d

This no longer compiles on recent versions of DMD :(

On Sunday, 29 January 2017 at 13:09:18 UTC, Nestor wrote:
> This no longer compiles on recent versions of DMD :(

Trivial fix though, it just needs to say "\n" instead of plain \n (it is missing quotes, D used to allow that for whatever stupid reason and has since been fixed).

Actually, tbh, I'm surprised it isn't a bigger fix needed given that that post is from 9 years ago!

On Sunday, 29 January 2017 at 13:45:12 UTC, Adam D. Ruppe wrote:
> On Sunday, 29 January 2017 at 13:09:18 UTC, Nestor wrote:
>> This no longer compiles on recent versions of DMD :(
>
> Trivial fix though, it just needs to say "\n" instead of plain \n (it is missing quotes, D used to allow that for whatever stupid reason and has since been fixed).
>
> Actually, tbh, I'm surprised it isn't a bigger fix needed given that that post is from 9 years ago!

Where is it missing the quotes? I tried fixing it like this, but it still doesn't compile:

"(){return members["~j.stringof~"];}\"\n\""

On Sunday, 29 January 2017 at 14:00:37 UTC, Nestor wrote:
> On Sunday, 29 January 2017 at 13:45:12 UTC, Adam D. Ruppe wrote:
>> On Sunday, 29 January 2017 at 13:09:18 UTC, Nestor wrote:
>>> This no longer compiles on recent versions of DMD :(
>>
>> Trivial fix though, it just needs to say "\n" instead of plain \n (it is missing quotes, D used to allow that for whatever stupid reason and has since been fixed).
>>
>> Actually, tbh, I'm surprised it isn't a bigger fix needed given that that post is from 9 years ago!
>
> Where is it missing the quotes? I tried fixing it like this, but it still doesn't compile:
>
> "(){return members["~j.stringof~"];}\"\n\""

Here :

 foreach(uint  u; FooCol.j) writef("%s ", u); writef(\n);

On Sunday, 29 January 2017 at 14:16:37 UTC, ezneh wrote:
> Here :
>
>  foreach(uint  u; FooCol.j) writef("%s ", u); writef(\n);

I see, but apparently this isn't the only issue. I replaced the whole unittest with this, and it still doesn't compile:

import std.stdio;
void main() {
  struct MyStruct {
    uint   i;
    float  j;
  }
  MyStruct data;
  Columns!(MyStruct) MyCols;
}

Problems this time were in the AfterLast function, which I modified like this:

string AfterLast(string s, char c) {
  foreach_reverse(int i, char d; s) if(c==d) return s[i+1..$];
  return s;
}

However there are still some errors which I don´t know how to fix:

columns1.d(45): Error: cannot implicitly convert expression (this) of type Columns!(MyStruct) to Columns!(MyStruct)*
columns1.d(63): Error: template instance columns1.Columns!(MyStruct) error instantiating


Line 63 is the declaration of MyCols, and line 45 would be thisÑ

At opIndex(uint i) { return At(this,i); }