return type based on content of an array

[Simen Kjærås]

On Wednesday, 21 February 2018 at 06:45:14 UTC, thorstein wrote:
> Hi,
>
> I'm going circles... ;) I read a string that contains an array 
> of unknown dimension like:
> a = [1,2,3,4] or
> a = [[1,2],[3,4]] or
> a = [[[1,2],[3,4]],[[5,6],[7,8]]]
>
> With that I want to perform specified operations e.g. also 
> provided on command line.
>
> Because at compile time the dimension of the array is unkown I 
> did not find any possibility to do something like:
>
> auto arr = func(a);
>
> where 'auto func(string str)' should return either a 1D, 2D, 3D 
> array and arr is not locked in an if(){} scope.
>
> Is there any way and What should I'm looking for?
>
> Thanks, thorstein

There's std.variant: https://dlang.org/phobos/std_variant

The code would probably be something like:

Algebraic!(int[], int[][], int[][][]) array;

if (value.is1D) {
     array = value.read1DArray();
} else if (value.is2D) {
     array = value.read2DArray();
} else {
     array = value.read3DArray();
}

And you'd grab the type of value you want by array.get!(int[][]).

--
   Simen