Freezable.WritePreamble Method

Reference

Definition

Namespace:: System.Windows

Assembly:: WindowsBase.dll

Important

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Verifies that the Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties.

protected:
 void WritePreamble();

protected void WritePreamble();

member this.WritePreamble : unit -> unit

Protected Sub WritePreamble ()

Exceptions

InvalidOperationException

The Freezable instance is frozen and cannot have its members written to.

Remarks

This method calls VerifyAccess to verify the threading context is accessible, and it throws an exception if the Freezable instance is already frozen.

Notes to Inheritors

Classes that derive from Freezable should call WritePreamble() before attempting to write to any members that are not dependency properties. If you call WritePreamble() in an API, you can omit a call to ReadPreamble().

Applies to

產品	版本
.NET Framework	3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
Windows Desktop	3.0, 3.1, 5, 6, 7, 8, 9, 10

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