Class inside a Struct?

[Ali Çehreli via Digitalmars-d-learn]

On 01/30/2015 01:28 PM, Ary Borenszweig wrote:

 > On 1/30/15 5:28 PM, Ali Çehreli wrote:
 >> On 01/30/2015 11:59 AM, chardetm wrote:
 >>
 >>  > struct Container {
 >>  >
 >>  >      private RedBlackTree!int _rbtree = new RedBlackTree!int;
 >>
 >> I think you are expecting the new expression to be be executed for every
 >> object individually. It is not the case: That new expression determines
 >> the initial value of the _rbtree for every single object of type
 >> Container. As a result, they will all be sharing the same tree.
 >>
 >> The best solution is
 >>
 >> 1) Remove the new expression:
 >> 2) Use a static opCall:
 >
 > Why not use this() ?

In fact, I think a better solution is to use a constructor that takes 
the tree:

     this(RedBlackTree!int rbtree)  // <-- good practice
                                    // ("parameterize from above")
     {
         _rbtree = rbtree;
     }

However, I thought that OP did not want the users know about that 
member. So, as you say, the next option that comes to mind is to use the 
default constructor:

     this()
     {
         _rbtree = new RedBlackTree!int;
     }

Unfortunately, D does not allow defining the default constructor for 
structs:

Error: constructor deneme.Container.this default constructor for structs 
only allowed with @disable and no body

The reason is, the default constructor happens to be the .init value of 
that type and it must be known at compile time.

Ali