BoolList.BeginUpdate() Method

Prevents the BoolList from being updated until the BoolList.EndUpdate method is called.

Namespace: DevExpress.ExpressApp.Utils

Assembly: DevExpress.ExpressApp.v18.2.dll

Declaration

public void BeginUpdate()
Public Sub BeginUpdate

The BeginUpdate and BoolList.EndUpdate methods are designed to implement batch modifications with a BoolList. After the BeginUpdate method has been called, and until a call to the BoolList.EndUpdate method, the BoolList's events will not be raised and the BoolList.ResultValue property value will not change. This allows you to prevent excessive updates when changing multiple key values at once. For this purpose, enclose the code that changes multiple keys within calls to these methods. The following code snippet illustrates this.

//...
mySimpleAction.Active.BeginUpdate();
mySimpleAction.Active["MyReason1"] = "true";
mySimpleAction.Active["MyReason2"] = "true";
mySimpleAction.Active["MyReason3"] = "true";
//...
mySimpleAction.Active.EndUpdate();

The BeginUpdate and EndUpdate methods use an internal counter to implement their functionality. The counter's initial value is 0. A call to the BeginUpdate method increments the counter by one. A call to the EndUpdate method decrements the counter by one, and if its new value is zero, a change notification is generated. This means that each call to BeginUpdate must be paired with a call to EndUpdate. If a call to BeginUpdate is made, but without a subsequent corresponding call to EndUpdate, or EndUpdate is not called because an exception occurred, the BoolList will no longer respond to changes. To ensure that EndUpdate is always called even if an exception occurs, wrap any calls to these methods in a try...finally statement.

See Also