Property initializers

From now on, you don't need to initialize properties in the constructor if those specific properties are not dependent on arguments passed to the construtor.

Let's say we have a ShoppingCart class which has a list of items.

public class ShoppingCart
{
    public List<Item> Items { get; set; }
}

public class Item
{

}

Now, the Items list is null (points to nothing). If we try, for example, to create a ShoppingCart instance and add something to the list, we will get an exception: NullReferenceException

var shoppingCart = new ShoppingCart();
shoppingCart.Items.Add(new Item());

Again, because the list was not initialized, meaning it wasn't set to anything.

We need to initialize it.

We could have done this through the constructor of the class, like so:

public class ShoppingCart
{
    public List<Item> Items { get; set; }

    public ShoppingCart()
    {
        Items = new List<Item>();
    }
}

But now, we can use property initializers:

public class ShoppingCart
{
    public List<Item> Items { get; set; } = new List<Item>();
}

Let's add an Added date for the Item class and set it to now as a property initializer:

public class Item
{
    public DateTime Added { get; } = DateTime.Now;
}

The same principle applies here, also when there is only a get accessor (this property cannot be changed after the instance was created – readonly).

var item = new Item();
item.Added = DateTime.Now; // this is an error

But, we can change it when we create it only through a constructor:

public Item(DateTime added)
{
    Added = added;
}

And here we pass the value:

var item = new Item(DateTime.Now);

# Property initializers

Property initializers