ImportedFromTypeLibAttribute Class

Definition

Namespace:

System.Runtime.InteropServices

Assembly:

System.Runtime.InteropServices.dll

Source:

ImportedFromTypeLibAttribute.cs

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

public ref class ImportedFromTypeLibAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Assembly, Inherited=false)]
public sealed class ImportedFromTypeLibAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Assembly, Inherited=false)>]
type ImportedFromTypeLibAttribute = class
    inherit Attribute

Public NotInheritable Class ImportedFromTypeLibAttribute
Inherits Attribute

Inheritance

Object

Attribute

ImportedFromTypeLibAttribute

Attributes

AttributeUsageAttribute

Examples

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;
   }
};

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 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;
        }
    }
}

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 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

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.

Constructors

ImportedFromTypeLibAttribute(String)

Initializes a new instance of the ImportedFromTypeLibAttribute class with the name of the original type library file.

Properties

TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)
Value	Gets the name of the original type library file.

Methods

Equals(Object)	Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute)
GetHashCode()	Returns the hash code for this instance. (Inherited from Attribute)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• ComImportAttribute
• Tlbimp.exe (Type Library Importer)