Mimicing Python list of list

[Dandyvica via Digitalmars-d-learn]

On Monday, 26 October 2015 at 19:26:08 UTC, Meta wrote:
> On Monday, 26 October 2015 at 18:46:45 UTC, Dandyvica wrote:
>> Hi all,
>>
>> I'm trying to find out a solution to implement a generic tree 
>> or array container whose nodes
>> can either be elements or a subtree (or sub-array).
>>
>> Pretty much like you can do in Python:
>>
>> l = [1, 2, [1, 2, 3], 4]
>>
>> l is a list of (integers or list of integers).
>>
>> Any idea on how to do that?
>>
>> Thanks.
>
> It's a bit more involved than in Python as D is not a 
> dynamically typed language.
>
> import std.typecons;
> import std.stdio;
>
> struct Tree(T)
> {
> 	T payload;
> 	Tree!T[] children;
> }
>
> Tree!T tree(T)(T payload, Tree!T[] children...)
> {
> 	return Tree!T(payload, children.dup);
> }
>
> //Convenience overload because typeof(null)
> //does not implicitly convert to Tree!T[]
> Tree!T tree(T)(T payload, typeof(null))
> {
> 	return Tree!T(payload, null);
> }
>
> void printTree(T)(Tree!T tree)
> {
> 	writeln(tree.payload);
> 	foreach (child; tree.children)
> 	{
> 		printTree(child);
> 	}
> }
>
> void main()
> {
> 	auto intTree = tree(0,
> 		           tree(1,
> 		               tree(2)),
> 			   tree(3,
> 			       tree(4,
> 			           tree(5))),
> 			   tree(6,
> 			       tree(7)));
>
> 	printTree(intTree);
> }
>
> Otherwise, you an use std.variant.Variant or 
> std.variant.Algebraic.

Thanks Meta, great idea.

But does I'd like to have something like dynamic arrays and be 
able to do this:

class A(T) { T _v; this(T v) { _v = v; }  }

auto myContainer = MyContainerArray!(A!int)();

myContainer ~= new A!int(1);
myContainer ~= new A!int(2);

auto myInnerContainer = MyContainerArray!(A!int)();
myInnerContainer ~= new A!int(3);
myInnerContainer ~= new A!int(4);

myContainer ~= myInnerContainer;
myContainer ~= new A!int(5);

I don't know if your implementation allows this?