EmptyControlCollection Constructor (Control)
.NET Framework (current version)
Initializes a new instance of the EmptyControlCollection class.
Assembly: System.Web (in System.Web.dll)
The following code example attempts to populate a control with child controls, causing an exception. This is because the container control does not allow child controls. The following is the command line used to build the executable.
vbc /r:System.dll /r:System.Web.dll /t:library
/out:myWebAppPath/bin/vb_myEmptyControlCollection.dll
myEmptyControlCollection.vb
' File name: emptyControlCollection.vb. Imports System Imports System.Web Imports System.Web.UI Imports System.Web.UI.WebControls Imports System.Collections Namespace CustomControls Public Class MyVB_EmptyControl Inherits Control <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _ Protected Overrides Function CreateControlCollection() As ControlCollection ' Function Name: CreateControlCollection. ' Denies the creation of any child control by creating an empty collection. ' Generates an exception if an attempt to create a child control is made. Return New EmptyControlCollection(Me) End Function <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _ Protected Overrides Sub CreateChildControls() ' Sub Name: CreateChildControls. ' Populates the child control collection (Controls). ' Note: This function will cause an exception because the control does not allow ' child controls. Dim text As LiteralControl text = New LiteralControl("<h5>Composite Controls</h5>") Controls.Add(text) End Sub End Class End Namespace
The following code example uses the empty custom control defined above. When running this example, you will get an exception. Notice that the values shown in the Register directive reflect the previous command line.
.NET Framework
Available since 1.1
Available since 1.1
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