On Monday, 23 November 2020 at 01:20:04 UTC, data pulverizer
wrote:
Hi all,
I am trying to construct a tree data structure composed of
differently (statically) typed nodes. The basic case is a
binary tree. So you have a node like:
```
struct Node(T)
{
T value;
Node* next;
Node* prev;
}
void main()
{
auto x = Node!(int)(2);
auto y = Node!(double)(3.2);
x.next = &y; //gives error
}
```
Error: cannot implicitly convert expression & y of type
Node!double* to Node!int*
So implicity Node!(T) will produce an object with prev, and
next type Node!(T)*. But once I give them different types:
```
struct Node(T, P, N)
{
T value;
Node!(P...)* prev;
Node!(N...)* next;
}
```
I can no longer specify the types at all, they become
circularly referenced. Would appreciate the solution to this.
Many thanks.
If you want to keep things simple, use OOP (classes).
If you need to use structs, the "sumtype" may be just what you
need (it's a bit more lightweight than std.algebraic in the
standard library). If you want to implement this yourself then
you need to write something called a tagged union.
