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Freezable.WritePreamble Method

.NET Framework 4.5

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.

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

Syntax

C++

'Declaration
Protected Sub WritePreamble

Exceptions

Exception	Condition
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.

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Platforms

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.

Reference

Freezable Class

System.Windows Namespace

ReadPreamble

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