• thorstein (15/15) Feb 20 2018 Hi,
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (14/29) Feb 21 2018 There's std.variant: https://dlang.org/phobos/std_variant
• Steven Schveighoffer (18/39) Feb 21 2018 If you want a specific type that the type system cares about, you have

thorstein <torsten.lange mail.de> writes:

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

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

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

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 2/21/18 1:45 AM, 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?
 

If you want a specific type that the type system cares about, you have 
to implement every possibility. Then you can use Variant.

But if you want a recursive strategy, where you need the dimensions at 
runtime only, then you can write a struct with a tagged union which 
gives you all the info you need:

struct NDimArray
{
    size_t dimensions; // if 0, then this is a value
    union {
    	NDimArray[] elements;
         int value;
    }
}

You can probably figure out the rest. Probably you can eliminate the 
dimensions field somehow to save space.

This is how things like JSON DOM structures work.

-Steve