AppDomain.CreateComInstanceFrom Method
Definition
Important
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Creates a new instance of a specified COM type.
Overloads
CreateComInstanceFrom(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. |
CreateComInstanceFrom(String, String, Byte[], AssemblyHashAlgorithm) |
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. |
CreateComInstanceFrom(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.
public:
System::Runtime::Remoting::ObjectHandle ^ CreateComInstanceFrom(System::String ^ assemblyName, System::String ^ typeName);
public System.Runtime.Remoting.ObjectHandle CreateComInstanceFrom (string assemblyName, string typeName);
member this.CreateComInstanceFrom : string * string -> System.Runtime.Remoting.ObjectHandle
Public Function CreateComInstanceFrom (assemblyName As String, typeName As String) As ObjectHandle
Parameters
- assemblyName
- String
The name of a file containing an assembly that defines the requested type.
- typeName
- String
The name of the requested type.
Returns
An object that is a wrapper for the new instance specified by typeName
. The return value needs to be unwrapped to access the real object.
Exceptions
assemblyName
or typeName
is null
.
The type cannot be loaded.
The operation is attempted on an unloaded application domain.
No public parameterless constructor was found.
assemblyName
is not found.
typeName
is an abstract class.
-or-
This member was invoked with a late-binding mechanism.
The caller cannot provide activation attributes for an object that does not inherit from MarshalByRefObject.
assemblyName
is an empty string ("").
assemblyName
is not a valid assembly.
An assembly or module was loaded twice with two different evidences.
The COM object that is being referred to is null
.
Examples
The following sample demonstrates
using namespace System;
using namespace System::Reflection;
using namespace System::Runtime::InteropServices;
[ComVisible(true)]
public ref class MyComVisibleType
{
public:
MyComVisibleType()
{
Console::WriteLine( "MyComVisibleType instantiated!" );
}
};
[ComVisible(false)]
public ref class MyComNonVisibleType
{
public:
MyComNonVisibleType()
{
Console::WriteLine( "MyComNonVisibleType instantiated!" );
}
};
void CreateComInstance( String^ typeName )
{
try
{
AppDomain^ currentDomain = AppDomain::CurrentDomain;
String^ assemblyName = currentDomain->FriendlyName;
currentDomain->CreateComInstanceFrom( assemblyName, typeName );
}
catch ( Exception^ e )
{
Console::WriteLine( e->Message );
}
}
int main()
{
CreateComInstance( "MyComNonVisibleType" ); // Fail!
CreateComInstance( "MyComVisibleType" ); // OK!
}
using System;
using System.Reflection;
using System.Runtime.InteropServices;
[ComVisible(true)]
class MyComVisibleType {
public MyComVisibleType() {
Console.WriteLine("MyComVisibleType instantiated!");
}
}
[ComVisible(false)]
class MyComNonVisibleType {
public MyComNonVisibleType() {
Console.WriteLine("MyComNonVisibleType instantiated!");
}
}
class CreateComInstanceFromSnippet {
public static void Main() {
CreateComInstance("MyComNonVisibleType"); // Fail!
CreateComInstance("MyComVisibleType"); // OK!
}
static void CreateComInstance(string typeName) {
try {
AppDomain currentDomain = AppDomain.CurrentDomain;
string assemblyName = currentDomain.FriendlyName;
currentDomain.CreateComInstanceFrom(assemblyName, typeName);
} catch (Exception e) {
Console.WriteLine(e.Message);
}
}
}
open System
open System.Runtime.InteropServices
[<ComVisible true>]
type MyComVisibleType() =
do
printfn "MyComVisibleType instantiated!"
[<ComVisible false>]
type MyComNonVisibleType() =
do
printfn "MyComNonVisibleType instantiated!"
let createComInstance typeName =
try
let currentDomain = AppDomain.CurrentDomain
let assemblyName = currentDomain.FriendlyName
currentDomain.CreateComInstanceFrom(assemblyName, typeName)
|> ignore
with e ->
printfn $"{e.Message}"
createComInstance "MyComNonVisibleType" // Fail!
createComInstance "MyComVisibleType" // OK!
Imports System.Reflection
Imports System.Runtime.InteropServices
<ComVisible(True)> _
Class MyComVisibleType
Public Sub New()
Console.WriteLine("MyComVisibleType instantiated!")
End Sub
End Class
<ComVisible(False)> _
Class MyComNonVisibleType
Public Sub New()
Console.WriteLine("MyComNonVisibleType instantiated!")
End Sub
End Class
Module Test
Sub Main()
CreateComInstance("MyComNonVisibleType") ' Fail!
CreateComInstance("MyComVisibleType") ' OK!
End Sub
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
End Module 'Test
Remarks
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.
See also
Applies to
CreateComInstanceFrom(String, String, Byte[], AssemblyHashAlgorithm)
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.
public:
System::Runtime::Remoting::ObjectHandle ^ CreateComInstanceFrom(System::String ^ assemblyFile, System::String ^ typeName, cli::array <System::Byte> ^ hashValue, System::Configuration::Assemblies::AssemblyHashAlgorithm hashAlgorithm);
public System.Runtime.Remoting.ObjectHandle CreateComInstanceFrom (string assemblyFile, string typeName, byte[] hashValue, System.Configuration.Assemblies.AssemblyHashAlgorithm hashAlgorithm);
member this.CreateComInstanceFrom : string * string * byte[] * System.Configuration.Assemblies.AssemblyHashAlgorithm -> System.Runtime.Remoting.ObjectHandle
Public Function CreateComInstanceFrom (assemblyFile As String, typeName As String, hashValue As Byte(), hashAlgorithm As AssemblyHashAlgorithm) As ObjectHandle
Parameters
- assemblyFile
- String
The name of a file containing an assembly that defines the requested type.
- typeName
- String
The name of the requested type.
- hashValue
- Byte[]
Represents the value of the computed hash code.
- hashAlgorithm
- AssemblyHashAlgorithm
Represents the hash algorithm used by the assembly manifest.
Returns
An object that is a wrapper for the new instance specified by typeName
. The return value needs to be unwrapped to access the real object.
Exceptions
assemblyFile
or typeName
is null
.
The type cannot be loaded.
The operation is attempted on an unloaded application domain.
No public parameterless constructor was found.
assemblyFile
is not found.
typeName
is an abstract class.
-or-
This member was invoked with a late-binding mechanism.
The caller cannot provide activation attributes for an object that does not inherit from MarshalByRefObject.
assemblyFile
is the empty string ("").
assemblyFile
is not a valid assembly.
An assembly or module was loaded twice with two different evidences.
The COM object that is being referred to is null
.
Remarks
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.
See also
Applies to
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