Deborah's Developer MindScape

One of the new features in VB 10.0 is auto-implemented properties. Auto-implemented properties are a shorter syntax for your property statements that automatically implement a backing field so you don’t have to manually define one.

(C# has had auto-implemented properties since C# 3.0. The examples here show both C# and VB for completeness.)

In this example, the Customer class has four properties as shown below.

In VB:

Public Class Customer
    Public Property CustomerId As Integer
    Public Property FirstName() As String
    Public Property LastName() As String
    Public Property EmailAddress() As String
End Class

In C#:

public class Customer
{
    public int CustomerId { get; set; }
    public string LastName { get; set; }
    public string FirstName { get; set; }
    public string EmailAddress { get; set; }
}

Without auto-implemented properties, the code is MUCH longer. The code shown above is functionally equivalent to the following:

In VB:

Public Class Customer
    Private _CustomerId As Integer 
    Public Property CustomerId() As Integer
        Get
            Return _CustomerId
        End Get
        Set(ByVal value As Integer)
            _CustomerId = value
        End Set
    End Property

    Private _FirstName As String
    Public Property FirstName() As String
        Get
            Return _FirstName
        End Get
        Set(ByVal value As String)
            _FirstName = value
        End Set
    End Property

    Private _LastName As String   
    Public Property LastName() As String
        Get
            Return _LastName
        End Get
        Set(ByVal value As String)
            _LastName = value
        End Set
    End Property

    Private _EmailAddress As String
    Public Property EmailAddress () As String
        Get
            Return _EmailAddress
        End Get
        Set(ByVal value As String)
            _EmailAddress = value
        End Set
    End Property
End Class

In C#:

public class Customer
{ 
    private int _CustomerId;
    public int CustomerId
    {
        get { return _CustomerId; }
        set { _CustomerId = value; }
    }

    private string _FirstName;
    public string FirstName
    {
        get { return _FirstName; }
        set { _FirstName = value; }
    }

    private string _LastName;
    public string LastName
    {
        get { return _LastName; }
        set { _LastName = value; }
    }

    private string _EmailAddress;
    public string EmailAddress
    {
        get { return _EmailAddress; }
        set { _EmailAddress = value; }
    }
}

Use auto-implemented properties whenever you need to define a property that does not require specialized code in the getter or setter.

Enjoy!

NOTE: For more information on the features and limitations of auto-implemented properties, see Auto-Implemented Properties Part II.