.NET Framework Class Library
ImportedFromTypeLibAttribute Class

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

Inheritance Hierarchy
SystemObject
   SystemAttribute
    System.Runtime.InteropServicesImportedFromTypeLibAttribute

Namespace:   System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)
Syntax
<[%$TOPIC/9awz85tc_en-us_VS_110_2_0_0_0_0%]([%$TOPIC/9awz85tc_en-us_VS_110_2_0_0_0_1%].Assembly, Inherited := False)> _
<[%$TOPIC/9awz85tc_en-us_VS_110_2_0_0_0_2%](True)> _
Public NotInheritable Class ImportedFromTypeLibAttribute _
	Inherits [%$TOPIC/9awz85tc_en-us_VS_110_2_0_0_0_3%]
[[%$TOPIC/9awz85tc_en-us_VS_110_2_0_1_0_0%]([%$TOPIC/9awz85tc_en-us_VS_110_2_0_1_0_1%].Assembly, Inherited = false)]
[[%$TOPIC/9awz85tc_en-us_VS_110_2_0_1_0_2%](true)]
public sealed class ImportedFromTypeLibAttribute : [%$TOPIC/9awz85tc_en-us_VS_110_2_0_1_0_3%]
[[%$TOPIC/9awz85tc_en-us_VS_110_2_0_2_0_0%]([%$TOPIC/9awz85tc_en-us_VS_110_2_0_2_0_1%]::Assembly, Inherited = false)]
[[%$TOPIC/9awz85tc_en-us_VS_110_2_0_2_0_2%](true)]
public ref class ImportedFromTypeLibAttribute sealed : public [%$TOPIC/9awz85tc_en-us_VS_110_2_0_2_0_3%]
[<[%$TOPIC/9awz85tc_en-us_VS_110_2_0_3_0_0%]>]
[<[%$TOPIC/9awz85tc_en-us_VS_110_2_0_3_0_1%]([%$TOPIC/9awz85tc_en-us_VS_110_2_0_3_0_2%].Assembly, Inherited = false)>]
[<[%$TOPIC/9awz85tc_en-us_VS_110_2_0_3_0_3%](true)>]
type ImportedFromTypeLibAttribute =  
    class 
        inherit [%$TOPIC/9awz85tc_en-us_VS_110_2_0_3_0_4%] 
    end
public final class ImportedFromTypeLibAttribute extends [%$TOPIC/9awz85tc_en-us_VS_110_2_0_4_0_0%]

The ImportedFromTypeLibAttribute type exposes the following members.

Constructors
  NameDescription
Public method ImportedFromTypeLibAttributeInitializes a new instance of the ImportedFromTypeLibAttribute class with the name of the original type library file.
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Properties
  NameDescription
Public property TypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
Public property ValueGets the name of the original type library file.
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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, 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.

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

Module A
	Public Function IsCOMAssembly(ByVal a As System.Reflection.Assembly) As Boolean 

		Dim AsmAttributes As Object() = a.GetCustomAttributes(GetType(ImportedFromTypeLibAttribute), True)
		If AsmAttributes.Length = 1 Then 
			Dim imptlb As ImportedFromTypeLibAttribute = AsmAttributes(0)
			Dim strImportedFrom As String = 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 
		End If 

		' This is not a COM assembly.
		Console.WriteLine("Assembly " + a.FullName + " is not imported from COM")

		Return False 
	End Function 
End Module
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;
		}
	}
}
using namespace System;
using namespace System::Reflection;
using namespace System::Runtime::InteropServices;

class ClassA
{
private:
   static bool IsCOMAssembly( Assembly^ a )
   {
      array<Object^>^AsmAttributes = a->GetCustomAttributes( ImportedFromTypeLibAttribute::typeid, true );
      if ( AsmAttributes->Length > 0 )
      {
         ImportedFromTypeLibAttribute^ imptlb = dynamic_cast<ImportedFromTypeLibAttribute^>(AsmAttributes[ 0 ]);
         String^ strImportedFrom = imptlb->Value;

         // Print out the name of the DLL from which the assembly is imported.
         Console::WriteLine( "Assembly {0} is imported from {1}", a->FullName, strImportedFrom );
         return true;
      }

      // This is not a COM assembly.
      Console::WriteLine( "Assembly {0} is not imported from COM", a->FullName );
      return false;
   }
};
Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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.