Cannot implement type with a collection initializer because it does not implement 'System.Collections.IEnumerable'

Question

I'm working in C# and XNA.

I have a class:

class Quad
    {
        public Texture2D Texture;
        public VertexPositionTexture[] Vertices = new VertexPositionTexture[4];
    }

And I'm trying to create a new instance of said class:

Quad tempQuad = new Quad() 
{
    Texture = QuadTexture,
    Vertices[0].Position = new Vector3(0, 100, 0),
    Vertices[0].Color = Color.Red
};

Which will then be added to a list of "Quad"s

QuadList.Add(tempQuad);

I keep either getting an error:

"Cannot implement type with a collection initializer because it does not implement 'System.Collections.IEnumerable'"

Or I get told that

Vertices does not exist in the current context.

Is there a reason I can't create class like this? Am I being dumb? Do I have to do it like this?:

Quad tempQuad = new Quad();

tempQuad.Vertices[0].Position = new Vector3(0, 100, 0);
tempQuad.Color = Color.Red;

QuadList.Add(tempQuad);

Is there a way around this at all? Any help would be greatly appreciated.

Answer 1

The object initialize syntax is expecting assignment to properties on the object you're initializing, but by attempting to assign to Vertices[0] you're trying to assign to properties of an index of a property on the object you're initializing(!).

You can use the object initialization syntax so long as you assign Vertices directly:

Quad tempQuad = new Quad() 
{
    Texture = QuadTexture,
    Vertices = new VertexPositionTexture[]
                {
                    new VertexPositionTexture 
                    {
                        Position = new Vector3(0, 100, 0),
                        Color = Color.Red
                    }, 
                    // ... define other vertices here
                }
};

As you can see, this gets pretty messy pretty quickly, so you'd probably be better off initializing the array outside of the object initialization:

var vertices = new VertexPositionTexture[]
                {
                    new VertexPositionTexture 
                    {
                        Position = new Vector3(0, 100, 0),
                        Color = Color.Red
                    }, 
                    // ... define other vertices here
                };

Quad tempQuad = new Quad() 
{
    Texture = QuadTexture,
    Vertices = vertices
};