C#

using System;

public class CartItem : IEquatable<cartitem> {
	#region Properties

    public int Quantity
    {
        get;
        set;
    }

	private int _productId;

	public int ProductId 
    {
		get 
        { 
            return _productId; 
        }
		set 
        {
			_productId = value;
		}
	}

	private Product _product = null;  

	public Product Prod 
    {
		get 
        {
			if (_product == null) 
            {
				_product = new Product(ProductId);
			}
			return _product;
		}
	}

	public string Description 
    {
		get 
        { 
            return Prod.Description; 
        }
	}

	public decimal UnitPrice 
    {
		get 
        { 
            return Prod.Price; 
        }
	}
    public string productname
    {
        get
        {
            return Prod.Productname;  
        }
    }

	public decimal TotalPrice 
    {
		get 
        { 
            return UnitPrice * Quantity; 
        }
	}

	#endregion

	public CartItem(int productId) 
    {
		this.ProductId = productId;
	}

	public bool Equals(CartItem item) 
    {
		return item.ProductId == this.ProductId;
	}
}

</cartitem>