EmptyControlCollection コンストラクタとは何？わかりやすく解説 Weblio辞書

.NET Framework クラスライブラリリファレンス

索引トップ用語の索引ランキング

EmptyControlCollection コンストラクタ

EmptyControlCollection クラスの新しいインスタンスを初期化します。

名前空間: System.Web.UI
アセンブリ: System.Web (system.web.dll 内)
構文

Visual Basic (宣言)

Public Sub New ( _
    owner As Control _
)

Visual Basic (使用法)

Dim owner As Control

Dim instance As New EmptyControlCollection(owner)

public EmptyControlCollection (
    Control owner
)

C++

public:
EmptyControlCollection (
    Control^ owner
)

public EmptyControlCollection (
    Control owner
)

JScript

public function EmptyControlCollection (
    owner : Control
)

パラメータ

owner: このコレクションを子コントロールのコレクションとして所有している Control。

使用例

子コントロールを持つコントロールを設定しようとして例外が発生するコード例を次に示します。この例外は、コンテナコントロールで子コントロールが許可されていないために発生します。実行可能ファイルを作成するために使用されるコマンドラインを次に示します。

Visual Basic

vbc /r:System.dll /r:System.Web.dll /t:library
       /out:myWebAppPath/bin/vb_myEmptyControlCollection.dll
       myEmptyControlCollection.vb

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

Visual Basic

' 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

/* 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);
      }
   }

}

/* File name: emptyControlCollection.jsl. */
import System.*;
import System.Web.*;
import System.Web.UI.*;
import System.Web.UI.WebControls.*;
import System.Collections.*;

// Defines a simple custom control.
public class MyJSL_EmptyControl extends Control
{
//    /** @attribute System.Security.Permissions.PermissionSet(
//        System.Security.Permissions.SecurityAction.Demand, Name =
 "FullTrust")
//     */
    protected 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);
    } //CreateControlCollection

    /** @attribute System.Security.Permissions.PermissionSet(
        System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")
     */
    protected 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>");
        get_Controls().Add(text);
    } //CreateChildControls
} //MyJSL_EmptyControl

上記で定義した空のカスタムコントロールを使用するコード例を次に示します。この例を実行すると、例外が発生します。Register ディレクティブに示される値には、前のコマンドラインが反映されます。

Visual Basic

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

<%@ 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>