csvReader: how to read only selected columns while the class Layout has extra field?

[Salih Dincer]

On Sunday, 2 October 2022 at 19:48:52 UTC, mw wrote:
> ```
>         text.csvReader!Layout(["b","c","a"]);  // Read only 
> these column
> ```
>
> The intention is very clear: only read the selected columns 
> from the csv, and for any other fields of class Layout, just 
> ignore (with the default D .init value).

Why don't you do this?  For example you can try the following?

     ```d
     import std.csv, std.math.algebraic : abs;

          string str = "a,b,c\nHello,65,63.63\n➊➋➂❹,123,3673.562";
          struct Layout
          {
              int value;
              double other;
              string name;
          }

          auto records = csvReader!Layout(str, ["b","c","a"]);

          Layout[2] ans;
          ans[0].name = "Hello";
          ans[0].value = 65;
          ans[0].other = 63.63;
          ans[1].name = "➊➋➂❹";
          ans[1].value = 123;
          ans[1].other = 3673.562;

          int count;
          foreach (record; records)
          {
              assert(ans[count].name == record.name);
              assert(ans[count].value == record.value);
      
        assert(abs(ans[count].other - record.other) < 0.00001);
              count++;
          }
          assert(count == ans.length);
     ```

SDB at 79