User defined types: Problems with ref

Chris wendlec at tcd.ie
Thu Jan 23 07:26:24 PST 2014


On Thursday, 23 January 2014 at 15:24:19 UTC, Chris wrote:
> Here's what I'm trying to do.
>
> struct Element(T) {
>     T x;
>     T y;
>
>     public void setX(T value) {
>       x = value;
>     }
>     // More fancy functions ...
> }
>
> I store Element(s) in an array and want to pass each one by 
> reference, which does not work.
>
>
> class Tree {
>
>     Element!string[] elements;
>
>     public ref auto createElement(string name) {
>       elements ~= Element!string(name);
>       return elements[$-1];
>     }
> }
>
> in main:
>
> auto tag = Element!string("first");
>
> The elements in Tree.elements and the ones in main are not the 
> same, instead I obtain a copy of each.
> How can I make them refer to the same Elements? If I have to 
> add a .ptr property to Element, how do I do that? Is that 
> possible at all or did I shoot myself in the foot with the 
> template?

Sorry in main it is:

auto tree = new Tree();
auto tag = tree.createElement("first");


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