Should I ignore InterfaceMethodsShouldBeCallableByChildTypes for WPF generated code?

Question

When using FxCop 1.36 for a WPF application with a single window that has yet to be modified, I get the InterfaceMethodsShouldBeCallableByChildTypes error with the following details:

    Target       : #System.Windows.Markup.IComponentConnector.Connect(System.Int32,System.Object)  (IntrospectionTargetMember)
    Resolution   : "Make 'MainWindow' sealed (a breaking change if 
                   this class has previously shipped), implement the method 
                   non-explicitly, or implement a new method that exposes 
                   the functionality of 'IComponentConnector.Connect(int,
                    object)' and is visible to derived classes."
    Help         : http://msdn2.microsoft.com/library/ms182153(VS.90).aspx  (String)
    Category     : Microsoft.Design  (String)
    CheckId      : CA1033  (String)
    RuleFile     : Design Rules  (String)
    Info         : "Explicit method implementations are defined with private 
                   accessibility. Classes that derive from classes with 
                   explicit method implementations and choose to re-declare 
                   them on the class will not be able to call into the 
                   base class implementation unless the base class has 
                   provided an alternate method with appropriate accessibility. 
                   When overriding a base class method that has been hidden 
                   by explicit interface implementation, in order to call 
                   into the base class implementation, a derived class 
                   must cast the base pointer to the relevant interface.
                    When calling through this reference, however, the 
                   derived class implementation will actually be invoked,
                    resulting in recursion and an eventual stack overflow."
    Created      : 08/12/2008 22:26:37  (DateTime)
    LastSeen     : 08/12/2008 22:41:05  (DateTime)
    Status       : Active  (MessageStatus)
    Fix Category : NonBreaking  (FixCategories)
}

Should this simply be ignored?

Answer 1

Depends on what you expect an inheriter to do.

If you are not expecting this class to be inherited then it should be sealed and the problem goes away.

If you are expecting it to be inherited then you are taking the ability of the inheriting class to override the interface methods and still call them (i.e. base.methodname()). If that is your intent then you can ignore the warning.

However, that is not expected behaviour for inheritable classes so you should expose the interface publicly (i.e. An implicit interface instead of an explicit interface).

Answer 2

Ignore it, this is standard code that is in every WPF application and you don't see people complaining about net being able to call IComponentConnector.Connect from derived classes - so it's probably safe.

In general I think you should handle FxCop output as suggestions that have to be considered carefully, I've got a lot of bad advice from FxCop in the past.