Friend (Visual Basic)
Specifies that one or more declared programming elements are accessible only from within the assembly that contains their declaration.
In many cases, you want programming elements such as classes and structures to be used by the entire assembly, not only by the component that declares them. However, you might not want them to be accessible by code outside the assembly (for example, if the application is proprietary). If you want to limit access to an element in this way, you can declare it by using the
Code in other classes, structures, and modules that are compiled to the same assembly can access all the
Friend elements in that assembly.
Friend access is often the preferred level for an application's programming elements, and
Friend is the default access level of an interface, a module, a class, or a structure.
You can use
Friend only at the module, interface, or namespace level. Therefore, the declaration context for a
Friend element must be a source file, a namespace, an interface, a module, a class, or a structure; it can't be a procedure.
You can also use the Protected Friend access modifier, which makes a class member accessible from within that class, from derived classes, and from the same assembly in which the class is defined. To restrict access to a member from within its class and from derived classes in the same assembly, you use the Private Protected access modifier.
For a comparison of
Friend and the other access modifiers, see Access levels in Visual Basic.
You can specify that another assembly is a friend assembly, which allows it to access all types and members that are marked as
Friend. For more information, see Friend Assemblies.
The following class uses the
Friend modifier to allow other programming elements within the same assembly to access certain members.
Class CustomerInfo Private p_CustomerID As Integer Public ReadOnly Property CustomerID() As Integer Get Return p_CustomerID End Get End Property ' Allow friend access to the empty constructor. Friend Sub New() End Sub ' Require that a customer identifier be specified for the public constructor. Public Sub New(ByVal customerID As Integer) p_CustomerID = customerID End Sub ' Allow friend programming elements to set the customer identifier. Friend Sub SetCustomerID(ByVal customerID As Integer) p_CustomerID = customerID End Sub End Class
You can use the
Friend modifier in these contexts: