AppDomain.CreateComInstanceFrom Method (String, String)
Creates a new instance of a specified COM type. Parameters specify the name of a file that contains an assembly containing the type and the name of the type.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
'Declaration Public Function CreateComInstanceFrom ( _ assemblyName As String, _ typeName As String _ ) As ObjectHandle
Parameters
- assemblyName
- Type: System.String
The name of a file containing an assembly that defines the requested type.
- typeName
- Type: System.String
The name of the requested type.
Return Value
Type: System.Runtime.Remoting.ObjectHandleAn object that is a wrapper for the new instance specified by typeName. The return value needs to be unwrapped to access the real object.
| Exception | Condition |
|---|---|
| ArgumentNullException | assemblyName or typeName is Nothing. |
| TypeLoadException | The type cannot be loaded. |
| AppDomainUnloadedException | The operation is attempted on an unloaded application domain. |
| MissingMethodException | No public parameterless constructor was found. |
| FileNotFoundException | assemblyName is not found. |
| MemberAccessException | typeName is an abstract class. -or- This member was invoked with a late-binding mechanism. |
| NotSupportedException | The caller cannot provide activation attributes for an object that does not inherit from MarshalByRefObject. |
| ArgumentException | assemblyName is an empty string (""). |
| BadImageFormatException | assemblyName is not a valid assembly. |
| FileLoadException | An assembly or module was loaded twice with two different evidences. |
| NullReferenceException | The COM object that is being referred to is Nothing. |
Use this method to create objects remotely without having to load the type locally.
The return value must to be unwrapped to access the real object.
A System.Runtime.InteropServices.ComVisibleAttribute attribute with a value of true must be applied either explicitly or by default to the COM type for this method to create an instance of that type; otherwise, TypeLoadException is thrown.
The following sample demonstrates
Imports System Imports System.Reflection Imports System.Runtime.InteropServices <ComVisible(True)> _ Class MyComVisibleType Public Sub New() Console.WriteLine("MyComVisibleType instantiated!") End Sub 'New End Class 'MyComVisibleType <ComVisible(False)> _ Class MyComNonVisibleType Public Sub New() Console.WriteLine("MyComNonVisibleType instantiated!") End Sub 'New End Class 'MyComNonVisibleType Module Test Sub Main() CreateComInstance("MyComNonVisibleType") ' Fail! CreateComInstance("MyComVisibleType") ' OK! End Sub 'Main Sub CreateComInstance(typeName As String) Try Dim currentDomain As AppDomain = AppDomain.CurrentDomain Dim assemblyName As String = currentDomain.FriendlyName currentDomain.CreateComInstanceFrom(assemblyName, typeName) Catch e As Exception Console.WriteLine(e.Message) End Try End Sub 'CreateComInstance End Module 'Test
- FileIOPermissionAccess
for the ability to access the location of the assembly. Associated enumeration: FileIOPermissionAccess.PathDiscovery
- FileIOPermissionAccess
for the ability to read the file containing the assembly manifest. Associated enumeration: FileIOPermissionAccess.Read
- WebPermission
for the ability to access the location of the assembly if the assembly is not local.
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.
