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CA1410: COM registration methods should be matched

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Applies to: yesVisual Studio noVisual Studio for Mac

Note

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Item Value
RuleId CA1410
Category Microsoft.Interoperability
Breaking change Non-breaking

Cause

A type declares a method that is marked with the System.Runtime.InteropServices.ComRegisterFunctionAttribute attribute but does not declare a method that is marked with the System.Runtime.InteropServices.ComUnregisterFunctionAttribute attribute, or vice versa.

Rule description

For Component Object Model (COM) clients to create a .NET type, the type must first be registered. If it is available, a method that is marked with the ComRegisterFunctionAttribute attribute is called during the registration process to run user-specified code. A corresponding method that is marked with the ComUnregisterFunctionAttribute attribute is called during the unregistration process to reverse the operations of the registration method.

How to fix violations

To fix a violation of this rule, add the corresponding registration or unregistration method.

When to suppress warnings

Do not suppress a warning from this rule.

Example

The following example shows a type that violates the rule. The commented code shows the fix for the violation.

using System;
using System.Runtime.InteropServices;

[assembly: ComVisible(true)]
namespace InteroperabilityLibrary
{
   public class ClassToRegister
   {
   }

   public class ComRegistration
   {
      [ComRegisterFunction]
      internal static void RegisterFunction(Type typeToRegister) {}

//      [ComUnregisterFunction]
//      internal static void UnregisterFunction(Type typeToRegister) {}
   }
}

Imports System
Imports System.Runtime.InteropServices

<Assembly: ComVisibleAttribute(True)>
Namespace InteroperabilityLibrary

   Public Class ClassToRegister
   End Class

   Public Class ComRegistration

      <ComRegisterFunctionAttribute> _ 
      Friend Shared Sub RegisterFunction(typeToRegister As Type)
      End Sub

'      <ComUnregisterFunctionAttribute> _ 
'      Friend Shared Sub UnregisterFunction(typeToRegister As Type)
'      End Sub

   End Class

End Namespace

CA1411: COM registration methods should not be visible

See also