ComCompatibleVersionAttribute Class
Indicates to a COM client that all classes in the current version of an assembly are compatible with classes in an earlier version of the assembly.
For a list of all members of this type, see ComCompatibleVersionAttribute Members.
System.Object
System.Attribute
System.Runtime.InteropServices.ComCompatibleVersionAttribute
[Visual Basic] <AttributeUsage(AttributeTargets.Assembly)> NotInheritable Public Class ComCompatibleVersionAttribute Inherits Attribute [C#] [AttributeUsage(AttributeTargets.Assembly)] public sealed class ComCompatibleVersionAttribute : Attribute [C++] [AttributeUsage(AttributeTargets::Assembly)] public __gc __sealed class ComCompatibleVersionAttribute : public Attribute [JScript] public AttributeUsage(AttributeTargets.Assembly) class ComCompatibleVersionAttribute extends Attribute
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Remarks
You can apply this attribute to assemblies.
By default, the Type Library Exporter (Tlbexp.exe) uses an assembly's version number to calculate class identifiers (CLSIDs). All public, COM-visible classes receive new CLSIDs each time you export a new assembly version.
You can apply the System.Runtime.InteropServices.ComCompatibleVersionAttribute.ComCompatibleVersionAttribute attribute to force all CLSIDs for classes in the current version of an assembly to be the same as CLSIDs for classes in an earlier version of the assembly. As long as the CLSIDs remain the same, a legacy COM application can use the later version of a compatible assembly after you uninstall the original assembly. If you apply the System.Runtime.InteropServices.GuidAttribute to a class to explicitly set its CLSID, the System.Runtime.InteropServices.ComCompatibleAttribute has no effect.
The properties of this attribute combine to form the four parts of an assembly version. Always specify the lowest version that the current assembly is backward compatible with so that version is used to calculate all CLSIDs in the assembly.
Example
[Visual Basic, C#] The following example shows how to specify assembly version 1.0.0.0 in an assembly with a higher version number. Regardless of the new assembly version, all CLSIDs in the assembly are generated using version 1.0.0.0 instead of using the current assembly version.
[Visual Basic] Imports System Imports System.Runtime.Interop Assembly: AssemblyVersion ("3.0.0.0") Assembly: ComCompatibleVersionAttribute(1,0,0,0) Module MyNamespace Public Class MyClass ' Insert code. End Class [C#] using System; using System.Runtime.InteropServices; [Assembly: AssemblyVersion ("3.0.0.0") [Assembly: ComCompatibleVersion(1,0,0,0)] namespace MyNamespace { class MyClass { // Insert code. } }
[C++, JScript] No example is available for C++ or JScript. To view a Visual Basic or C# example, click the Language Filter button
in the upper-left corner of the page.
Requirements
Namespace: System.Runtime.InteropServices
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family
Assembly: Mscorlib (in Mscorlib.dll)
See Also
ComCompatibleVersionAttribute Members | System.Runtime.InteropServices Namespace | GuidAttribute | Type Library Exporter (Tlbexp.exe)