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WeakEventManager.ListenerList.BeginUse Method

Declares the list to be in use. This prevents direct changes to the list during iterations of the list items.

Namespace:  System.Windows
Assembly:  WindowsBase (in WindowsBase.dll)

public bool BeginUse()

Return Value

Type: System.Boolean
true if the list was already declared to be in use; otherwise, false.

A WeakEventManager implementation should call BeginUse before iterating through the list to deliver an event to the listeners, and should call EndUse when it is done. This prevents another caller from modifying the list while the iteration for purposes of event delivery is in progress. If the list is modified during this time, then the list is cloned. If the list is cloned, then PrepareForWriting returns true, which means that you have missed a recent listener change in the last delivery.

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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