Type.GetTypeFromCLSID Method (Guid, Boolean)

 

Gets the type associated with the specified class identifier (CLSID), specifying whether to throw an exception if an error occurs while loading the type.

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

Public Shared Function GetTypeFromCLSID (
	clsid As Guid,
	throwOnError As Boolean
) As Type

Parameters

clsid
Type: System.Guid

The CLSID of the type to get.

throwOnError
Type: System.Boolean

true to throw any exception that occurs.

-or-

false to ignore any exception that occurs.

Return Value

Type: System.Type

System.__ComObject regardless of whether the CLSID is valid.

The GetTypeFromCLSID method supports late-bound access to unmanaged COM objects from .NET Framework apps when you know the COM object's class identifier (CLSID). The class identifier for COM classes is defined in the HKEY_CLASSES_ROOT\CLSID key of the registry. You can retrieve the value of the IsCOMObject property to determine whether the type returned by this method is a COM object.

System_CAPS_tipTip

You can call the GetTypeFromProgID method for late-bound access to COM objects whose programmatic identifier (ProgID) you know.

Instantiating an unmanaged COM object from its CLSID is a two-step process:

  1. Get a Type object that represents the __ComObject that corresponds to the CLSID by calling the GetTypeFromCLSID method.

  2. Call the Activator.CreateInstance(Type) method to instantiate the COM object.

See the example for an illustration.

Exceptions such as OutOfMemoryException will be thrown when specifying true for throwOnError, but it will not fail for unregistered CLSIDs.

Notes to Callers:

This method is intended for use when working with COM objects, not with .NET Framework objects. All managed objects, including those that are visible to COM (that is, their ComVisibleAttribute attribute is true) have a GUID that is returned by the GUID property. Although the method returns a Type object that corresponds to the GUID for .NET Framework objects, you can't use that Type object to create a type instance by calling the Activator.CreateInstance method, as the following example shows.

Imports System.Runtime.InteropServices

<Assembly:ComVisible(True)>

' Define two classes, and assign one an explicit GUID.
<GuidAttribute("d055cba3-1f83-4bd7-ba19-e22b1b8ec3c4")>
Public Class ExplicitGuid
End Class

Public Class NoExplicitGuid
End Class

Module Example
   Public Sub Main()
      Dim explicitType As Type = GetType(ExplicitGuid)
      Dim explicitGuid As Guid = explicitType.GUID

      ' Get type of ExplicitGuid from its GUID.
      Dim explicitCOM As Type = Type.GetTypeFromCLSID(explicitGuid)
      Console.WriteLine("Created {0} type from CLSID {1}",
                        explicitCOM.Name, explicitGuid)

      ' Compare the two type objects.
      Console.WriteLine("{0} and {1} equal: {2}",
                        explicitType.Name, explicitCOM.Name,
                        explicitType.Equals(explicitCOM))                  

      ' Instantiate an ExplicitGuid object.
      Try 
         Dim obj As Object = Activator.CreateInstance(explicitCOM)
         Console.WriteLine("Instantiated a {0} object", obj.GetType().Name)
      Catch e As COMException
         Console.WriteLine("COM Exception:{1}{0}{1}", e.Message, vbCrLf)   
      End Try 

      Dim notExplicit As Type = GetType(NoExplicitGuid)
      Dim notExplicitGuid As Guid = notExplicit.GUID

      ' Get type of ExplicitGuid from its GUID.
      Dim notExplicitCOM As Type = Type.GetTypeFromCLSID(notExplicitGuid)
      Console.WriteLine("Created {0} type from CLSID {1}",
                        notExplicitCOM.Name, notExplicitGuid)

      ' Compare the two type objects.
      Console.WriteLine("{0} and {1} equal: {2}",
                        notExplicit.Name, notExplicitCOM.Name,
                        notExplicit.Equals(notExplicitCOM))                  

      ' Instantiate an ExplicitGuid object.
      Try 
         Dim obj As Object = Activator.CreateInstance(notExplicitCOM)
         Console.WriteLine("Instantiated a {0} object", obj.GetType().Name)
      Catch e As COMException
         Console.WriteLine("COM Exception:{1}{0}{1}", e.Message, vbCrLf)   
      End Try 
   End Sub
End Module
' The example displays the following output:
'       Created __ComObject type from CLSID d055cba3-1f83-4bd7-ba19-e22b1b8ec3c4
'       ExplicitGuid and __ComObject equal: False
'       COM Exception:
'       Retrieving the COM class factory for component with CLSID 
'       {D055CBA3-1F83-4BD7-BA19-E22B1B8EC3C4} failed due to the following error: 
'       80040154 Class not registered 
'       (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)).
'       
'       Created __ComObject type from CLSID 74f03346-a718-3516-ac78-f351c7459ffb
'       NoExplicitGuid and __ComObject equal: False
'       COM Exception:
'       Retrieving the COM class factory for component with CLSID 
'       {74F03346-A718-3516-AC78-F351C7459FFB} failed due to the following error: 
'       80040154 Class not registered 
'       (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)).

Instead, the GetTypeFromCLSID should only be used to retrieve the GUID of an unmanaged COM object, and the resultingType object that is passed to the Activator.CreateInstancemethod must represent an unmanaged COM object.

The following example uses the CLSID of the Microsoft Word Application object to retrieve a COM type that represents the Microsoft Word application. It then instantiates the type by calling the Activator.CreateInstance method, and closes it by calling the Application.Quit method. An exception is thrown if an error occurs while loading the type.

Imports System.Reflection
Imports System.Runtime.InteropServices

Module Example
   Private Const WORD_CLSID As String = "{000209FF-0000-0000-C000-000000000046}"

   Public Sub Main()
      ' Start an instance of the Word application.
      Try
         Dim word As Type = Type.GetTypeFromCLSID(Guid.Parse(WORD_CLSID), True)
         Console.WriteLine("Instantiated Type object from CLSID {0}",
                           WORD_CLSID)
         Dim wordObj As Object = Activator.CreateInstance(word)
         Console.WriteLine("Instantiated {0}", 
                           wordObj.GetType().FullName)

         ' Close Word.
         word.InvokeMember("Quit", BindingFlags.InvokeMethod, Nothing, 
                           wordObj, New Object() { 0, 0, False } )
      ' The method can throw any of a number of unexpected exceptions.
      Catch e As Exception
         Console.WriteLine("Unable to instantiate an object for {0}", WORD_CLSID)
      End Try
   End Sub
End Module
' The example displays the following output:
'    Instantiated Type object from CLSID {000209FF-0000-0000-C000-000000000046}
'    Instantiated Microsoft.Office.Interop.Word.ApplicationClass

.NET Framework
Available since 1.1
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