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ImportedFromTypeLibAttribute Class

Indicates that the types defined within an assembly were originally defined in a type library.

System.Object
  System.Attribute
    System.Runtime.InteropServices.ImportedFromTypeLibAttribute

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

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

The ImportedFromTypeLibAttribute type exposes the following members.

  NameDescription
Public methodImportedFromTypeLibAttributeInitializes a new instance of the ImportedFromTypeLibAttribute class with the name of the original type library file.
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  NameDescription
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
Public propertyValueGets the name of the original type library file.
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  NameDescription
Public methodEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Public methodGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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You can apply this attribute to assemblies, although the Tlbimp.exe (Type Library Importer) typically applies it for you when it a type library.

The primary use of the attribute is to capture the original source of the type information. For example, you can import A.tlb as an interop assembly called A.dll and have assembly B.dll reference A.dll. When you export B.dll to B.tlb, this attribute causes the references in B.tlb that point to A.dll to point instead to A.tlb. This should not be confused with the ComImportAttribute, which specifies that an individual type is implemented in COM.

using System;
using System.Reflection;
using System.Runtime.InteropServices;

namespace A
{
	class ClassA
	{
		public static bool IsCOMAssembly( Assembly a )
		{
			object[] AsmAttributes = a.GetCustomAttributes( typeof( ImportedFromTypeLibAttribute ), true );
			if( AsmAttributes.Length > 0 )
			{
				ImportedFromTypeLibAttribute imptlb = ( ImportedFromTypeLibAttribute )AsmAttributes[0];
				string strImportedFrom  = imptlb.Value;
				    
				// Print out the the name of the DLL from which the assembly is imported.
				Console.WriteLine( "Assembly " + a.FullName + " is imported from " + strImportedFrom );
			
				return true;
			}  
			// This is not a COM assembly.
			Console.WriteLine( "Assembly " + a.FullName + " is not imported from COM" );
			return false;
		}
	}
}

.NET Framework

Supported in: 4.5.3, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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.

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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