dynamic get from variantArray() data table

[Alex Parrill via Digitalmars-d-learn]

On Tuesday, 13 October 2015 at 15:17:15 UTC, data pulverizer 
wrote:
> Hi,
>
> I am trying to use variantArray() as a data table object to 
> hold columns each of which is an array of a specific type. I 
> need to be able to get values from data table but I am having 
> problems ...
>
>
> import std.stdio; // i/o
> import std.variant; // type variations
>
> void main(){
>   // Columns of the table
>   string[] names = ["walter", "paul", "jeff", "andrie"];
>   int[] age = [55, 62, 27, 52];
>   string[] language = ["D", "Haskell", "Julia", "D"];
>   Variant[] dt = variantArray(names, age, language);
>
>   foreach(col; dt){
>     foreach(el; col){
>       // here I try a kind of dynamic cast operator
>       auto x = el.get!(type(el)); // gives error
>       write(x);
>     }
>     write("\n");
>   }
> }
>
> data_table.d(37): Error: cannot infer type for el
> data_table.d(38): Error: undefined identifier 'el'
>
> Help
>
> DP

You're trying to iterate over a `Variant`, which isn't 
implemented.

You don't want to use a variant here anyway; you should use a 
struct or tuple for each entry in the table.



import std.typecons;

alias Entry = Tuple!(string, int, string);

void main() {
     auto table = [Entry("walter", 55, "D"), Entry("paul", 62, 
"Haskell"), ... ]; // complete array
     foreach(entry; table) {
         writeln(entry.expand);
     }
}