Parameter.OnParameterChanged Parameter.OnParameterChanged Parameter.OnParameterChanged Parameter.OnParameterChanged Method

定義

呼叫 OnParametersChanged(EventArgs) 集合的 ParameterCollection 方法,該集合包含給定的 Parameter 物件。Calls the OnParametersChanged(EventArgs) method of the ParameterCollection collection that contains the Parameter object.

protected:
 void OnParameterChanged();
protected void OnParameterChanged ();
member this.OnParameterChanged : unit -> unit
Protected Sub OnParameterChanged ()

範例

下列程式碼範例示範如何呼叫OnParameterChanged方法,以在參數的狀態變更時ParametersChanged引發事件。The following code example demonstrates how to call the OnParameterChanged method to raise the ParametersChanged event when the state of a parameter changes. 這個程式碼範例是針對Parameter類別總覽提供之較大範例的一部分。This code example is part of a larger example provided for the Parameter class overview.

// The Value property is a type safe convenience property
// used when the StaticParameter represents string data.
// It gets the string value of the DataValue property, and
// sets the DataValue property directly.
public string Value {
  get {
    object o = DataValue;
    if (o == null || !(o is string))
      return String.Empty;
    return (string)o;
  }
  set {
    DataValue = value;
    OnParameterChanged();
  }
}
' The Value property is a type safe convenience property
' used when the StaticParameter represents string data.
' It gets the string value of the DataValue property, and
' sets the DataValue property directly.
Public Property Value() As String
   Get
      Dim o As Object = DataValue
      If o Is Nothing OrElse Not TypeOf o Is String Then
         Return String.Empty
      End If
      Return CStr(o)
   End Get
   Set
      DataValue = value
      OnParameterChanged()
   End Set
End Property

備註

如果物件不包含ParameterCollection在集合中,則呼叫OnParameterChanged方法不會有任何作用。 ParameterIf the Parameter object is not contained by a ParameterCollection collection, calling the OnParameterChanged method has no effect. 如果物件包含ParameterCollection在集合中, OnParameterChanged則會引發集合ParameterCollection.ParametersChanged的事件。 ParameterIf the Parameter object is contained by a ParameterCollection collection, OnParameterChanged raises the ParameterCollection.ParametersChanged event of the collection.

如果集合包含在資料來源控制項ParameterCollection.ParametersChanged中,事件會引發資料來源控制項的DataSourceChanged事件,導致任何資料繫結控制項重新系結。 ParameterCollectionIf the ParameterCollection collection is contained by a data source control, the ParameterCollection.ParametersChanged event raises the data source control's DataSourceChanged event, causing any data-bound controls to rebind.

引發事件會透過委派叫用此事件處理常式。Raising an event invokes the event handler through a delegate. 如需詳細資訊, 請參閱處理和引發事件For more information, see Handling and Raising Events.

OnParameterChanged 方法也允許衍生類別處理事件,而不用附加委派。The OnParameterChanged method also allows derived classes to handle the event without attaching a delegate. 這是在衍生類別中處理事件的慣用技巧。This is the preferred technique for handling the event in a derived class.

給繼承者的注意事項

當在衍生類別中覆寫 OnParameterChanged() 時,請確定呼叫基底類別的 OnParameterChanged() 方法,使已註冊的委派能接收到事件。When overriding OnParameterChanged() in a derived class, be sure to call the base class's OnParameterChanged() method so that registered delegates receive the event.

適用於

另請參閱