Type.GetTypeFromCLSID Method (Guid, String, Boolean)
Gets the type associated with the specified class identifier (CLSID) from the specified server, specifying whether to throw an exception if an error occurs while loading the type.
Assembly: mscorlib (in mscorlib.dll)
Public Shared Function GetTypeFromCLSID ( clsid As Guid, server As String, throwOnError As Boolean ) As Type
Parameters
- clsid
-
Type:
System.Guid
The CLSID of the type to get.
- server
-
Type:
System.String
The server from which to load the type. If the server name is null, this method automatically reverts to the local machine.
- throwOnError
-
Type:
System.Boolean
true to throw any exception that occurs.
-or-
false to ignore any exception that occurs.
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.
Tip |
|---|
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:
Get a Type object that represents the __ComObject that corresponds to the CLSID by calling the GetTypeFromCLSID method.
Call the Activator.CreateInstance(Type) method to instantiate the COM object.
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 theGUIDproperty. Although theGetTypeFromCLSIDmethod returns a Type object that corresponds to the GUID for a particular managed object, 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 from a server named computer17.central.contoso.com. 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() Try ' Start an instance of the Word application. Dim word As Type = Type.GetTypeFromCLSID(Guid.Parse(WORD_CLSID), "computer17.central.contoso.com", 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 variety of exceptions. Catch e As Exception Console.WriteLine("{0}: Unable to instantiate an object for {1}", e.GetType().Name, 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
Available since 1.1
