.NET Framework Class Library
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.

Inheritance Hierarchy
SystemObject
   SystemAttribute
    System.Runtime.InteropServicesComCompatibleVersionAttribute

Namespace:   System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)
Syntax
<[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_0_0_0%]([%$TOPIC/72k6x8bk_en-us_VS_110_2_0_0_0_1%].Assembly, Inherited := False)> _
<[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_0_0_2%](True)> _
Public NotInheritable Class ComCompatibleVersionAttribute _
	Inherits [%$TOPIC/72k6x8bk_en-us_VS_110_2_0_0_0_3%]
[[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_1_0_0%]([%$TOPIC/72k6x8bk_en-us_VS_110_2_0_1_0_1%].Assembly, Inherited = false)]
[[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_1_0_2%](true)]
public sealed class ComCompatibleVersionAttribute : [%$TOPIC/72k6x8bk_en-us_VS_110_2_0_1_0_3%]
[[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_2_0_0%]([%$TOPIC/72k6x8bk_en-us_VS_110_2_0_2_0_1%]::Assembly, Inherited = false)]
[[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_2_0_2%](true)]
public ref class ComCompatibleVersionAttribute sealed : public [%$TOPIC/72k6x8bk_en-us_VS_110_2_0_2_0_3%]
[<[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_3_0_0%]>]
[<[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_3_0_1%]([%$TOPIC/72k6x8bk_en-us_VS_110_2_0_3_0_2%].Assembly, Inherited = false)>]
[<[%$TOPIC/72k6x8bk_en-us_VS_110_2_0_3_0_3%](true)>]
type ComCompatibleVersionAttribute =  
    class 
        inherit [%$TOPIC/72k6x8bk_en-us_VS_110_2_0_3_0_4%] 
    end

The ComCompatibleVersionAttribute type exposes the following members.

Constructors
  NameDescription
Public method ComCompatibleVersionAttributeInitializes a new instance of the ComCompatibleVersionAttribute class with the major version, minor version, build, and revision numbers of the assembly.
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Properties
  NameDescription
Public property BuildNumberGets the build number of the assembly.
Public property MajorVersionGets the major version number of the assembly.
Public property MinorVersionGets the minor version number of the assembly.
Public property RevisionNumberGets the revision number of the assembly.
Public property TypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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Methods
  NameDescription
Public method EqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Public method GetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public method GetTypeGets the Type of the current instance. (Inherited from Object.)
Public method IsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public method MatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Public method ToStringReturns a string that represents the current object. (Inherited from Object.)
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Explicit Interface Implementations
  NameDescription
Explicit interface implemetation Private method _AttributeGetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeGetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeGetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeInvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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Remarks

You can apply this attribute to assemblies.

By default, the Tlbexp.exe (Type Library Exporter) 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 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.InteropServicesGuidAttribute to a class to explicitly set its CLSID, the ComCompatibleVersionAttribute 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.

Examples

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.

Imports System
Imports System.Reflection
Imports System.Runtime.InteropServices

<assembly: AssemblyVersion("3.0.0.0")>
<assembly: ComCompatibleVersion(1,0,0,0)>
Namespace MyNamespace
    Public Class TheClass
        ' Insert code. 
    End Class 
End Namespace
using System;
using System.Reflection;
using System.Runtime.InteropServices;

[assembly: AssemblyVersion("3.0.0.0")]
[assembly: ComCompatibleVersion(1,0,0,0)]
namespace MyNamespace
{
    public class TheClass
    {
        // Insert code.
    }
}
using namespace System;
using namespace System::Reflection;
using namespace System::Runtime::InteropServices;

[assembly: AssemblyVersion("3.0.0.0")];
[assembly: ComCompatibleVersion(1,0,0,0)];
namespace MyNamespace
{
    public ref class TheClass
    {
        // Insert code.
    };
};
Version Information

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
Platforms

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.

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.