User defined types: Problems with ref

[Chris]

On Thursday, 23 January 2014 at 15:34:38 UTC, FreeSlave wrote:
> 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[$-1];
>>    }
>> }
>>
>> in main:
>>
>> auto tag = Element!string("first");
>>
>> The elements in Tree.elements and the ones in main are not the 
>> same, instead I obtain a copy of each.
>> How can I make them refer to the same Elements? If I have to 
>> add a .ptr property to Element, how do I do that? Is that 
>> possible at all or did I shoot myself in the foot with the 
>> template?
>
> You can use pointer
>
> Tree tree = new Tree();
> Element!(string)* element = &tree.createElement("first");
>
> & is to get address of returned value element.
>
> You also can rewrite your function like this:
>
> public Element!(string)* createElement(string name) {
>         elements ~= Element!string(name);
>         return &elements[$-1];
>     }
>
> to return pointer without need to get address on caller side.

Thanks, that was fast! Yes I was tinkering around with pointers, 
but didn't get it right, you did. However, the output is still 
the same, i.e. two different sets:

// After creating and changing
<div id="1">
Hello, world!
<span>
</span>
</div>

// The Elements in Tree.elements:
[<div>
</div>
, <span>
</span>
]