PrimaryInteropAssemblyAttribute Class
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PrimaryInteropAssemblyAttribute Class


Indicates that the attributed assembly is a primary interop assembly.

Namespace:   System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)


[AttributeUsageAttribute(AttributeTargets.Assembly, Inherited = false, 
	AllowMultiple = true)]
public sealed class PrimaryInteropAssemblyAttribute : Attribute

System_CAPS_pubmethodPrimaryInteropAssemblyAttribute(Int32, Int32)

Initializes a new instance of the PrimaryInteropAssemblyAttribute class with the major and minor version numbers of the type library for which this assembly is the primary interop assembly.


Gets the major version number of the type library for which this assembly is the primary interop assembly.


Gets the minor version number of the type library for which this assembly is the primary interop assembly.


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)


Returns the hash code for this instance.(Inherited from Attribute.)


Gets the Type of the current instance.(Inherited from Object.)


When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

You can apply this attribute to assemblies, although the Tlbimp.exe (Type Library Importer) typically applies it for you when it imports a type library.

An interop assembly contains metadata that describes existing COM types, which are often already described in a COM type library. Tlbimp.exe produces interop assemblies from COM type libraries. Interop assemblies typically only contain metadata (no code). Primary interop assemblies are provided by the same publisher as the type library they describe, and provide the official definitions of the types defined with that type library. Primary interop assemblies are always signed by their publisher to ensure uniqueness.

You can generate a primary interop assembly from a type library in the following ways:

  • Run TlbImp.exe with the /primary option from the command line.

  • Apply the PrimaryInteropAssemblyAttribute at design time.

To specify a primary interop assembly in managed source code, you must apply the System.Runtime.InteropServices.GuidAttribute and PrimaryInteropAssemblyAttribute to the assembly at design time. The GuidAttribute on the primary interop assembly identifies the LIBID of the type library and the PrimaryInteropAssemblyAttribute identifies the version of the particular type library for which this assembly is the primary interop assembly. The PrimaryInteropAssemblyAttribute can appear multiple times if the assembly is the primary interop assembly for multiple versions of the same type library.

When using the types defined in a type library, always reference the primary interop assembly for that type library, rather than reimporting or redefining the types themselves. For guidelines and procedures on how to produce or use primary interop assemblies, see Primary Interop Assemblies. For a detailed description of the type library importing process, see Type Library to Assembly Conversion Summary.

.NET Framework
Available since 1.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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