EmptyControlCollection Constructor (Control)

 
System_CAPS_noteNote

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Initializes a new instance of the EmptyControlCollection class.

Namespace:   System.Web.UI
Assembly:  System.Web (in System.Web.dll)

public EmptyControlCollection(
	Control owner
)

Parameters

owner
Type: System.Web.UI.Control

The Control that owns this collection as its collection of child controls.

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.

csc /t:library /out:myWebAppPath/bin/cs_myEmptyControlCollection.dll
    myEmptyControlCollection.cs

/* File name: emptyControlCollection.cs. */

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;

namespace CustomControls
{

  // Defines a simple custom control.
  public class MyCS_EmptyControl : Control
  {
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
    protected override ControlCollection CreateControlCollection() 
    /*
     * 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(this);
     }

     [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
     protected override void CreateChildControls()
     /*
      * Function Name: CreateChildControls.
      * Populates the child control collection (Controls). 
      * Note: This function will cause an exception because the control does not allow 
      * child controls.
      */
      {
        // Create a literal control to contain the header and add it to the collection.
        LiteralControl text;
        text = new LiteralControl("<h5>Composite Controls</h5>");
        Controls.Add(text);
      }
   }

}

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.

<%@ Register TagPrefix="custom" Assembly="cs_myEmptyControlCollection" Namespace="CustomControls" %>
 <html>
  <body>
  <h1>Using an Empty Control </h1>
  <custom:MyCS_EmptyControl id="csEmptyControlId" runat="server"/>
  </body>
 </html>

.NET Framework
Available since 1.1
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