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Calling base implementation from base class? Messages   Related Types This message was discovered on microsoft.public.dotnet.framework.clr. Responses highlighted in red are from those people who are likely to be able to contribute good, authoratitive information to this discussion. They include Microsoft employees, MVP's and others who IMHO contribute well to these kinds of discussions. Post a new message to this list... Joel Is there a way to call a base class implementation of a protected method when Here's the scenario: class MyApp { public static Main() { D obj=new D(); obj.Method1(); } } class B { protected void Method1() { } protected void Method2() { //I want to call B's implementation of Method1 even though I'm running as D's implementation of Method2; //conceptually I want to do: this.base.Method1(); } } class D : B { override protected void Method1() { Method2(); } } Is this doable? TIA </joel> Reply to this message...        eSapient Depends much on what interface you want to expose. Did you try running your code? It would not run because B.Method1 is protected. So the first thing you need to do is make it public. But in that case, you would be changing the signature of A.Method1 which you are overriding and that is not allowed. The following will work, but may not exactly meet your requirements. class MyApp { public static void Main() { D d = new D(); d.Method2(); } } class B { protected virtual void Method1() { Console.WriteLine("Inside B.Method1()"); } } class D : B { public void Method2() { base.Method1(); } } "Joel" <Click here to reveal e-mail address> wrote in message news:Click here to reveal e-mail address... [Original message clipped] Reply to this message...        Joel Sorry, I pulled that sample out of thin air without testing it. Here's working code to illustrate the problem: using System; namespace ConsoleApplication4 { class Class1 { [STAThread] static void Main(string[] args) { Derived d=new Derived(); d.Method1(); } } class Base { public virtual void Method1() { Console.WriteLine("Base.Method1"); } public virtual void Method2() { Console.WriteLine("Base.Method2"); Method1(); } } class Derived : Base { public override void Method1() { Console.WriteLine("Derived.Method1"); base.Method2(); } } } This results in an endless loop of : Derived.Method1 Base.Method2 Derived.Method1 Base.Method2 because the call to Method1() in Base calls Derived's implementation. What I want is for the Method1 invocation in Base to call its (Base's) implementation of Method1. The desired output would be: Derived.Method1 Base.Method2 Base.Method1 Sorry I wasn't clearer before. "eSapient" <Click here to reveal e-mail address> wrote in message news:%Click here to reveal e-mail address... > Depends much on what interface you want to expose. Did you try running your [Original message clipped] Reply to this message...        Luc E. Mistiaen Wouldn't a cast like ((Base)this).Method1 () ; in your Method2 solve your problem? /LM "Joel" <Click here to reveal e-mail address> wrote in message news:Click here to reveal e-mail address... [Original message clipped] Reply to this message...        Jon Skeet [C# MVP] (VIP) Luc E. Mistiaen <Click here to reveal e-mail address> wrote: [Original message clipped] No, because it would still be called polymorphically. -- Jon Skeet - <Click here to reveal e-mail address> http://www.pobox.com/~skeet If replying to the group, please do not mail me too Reply to this message...        Joel Jon, Any ideas on how this can be accomplished? If it's not doable I wonder why? It doesn't seem to break any OO rules. </joel> "Jon Skeet [C# MVP]" <Click here to reveal e-mail address> wrote in message news:Click here to reveal e-mail address... [Original message clipped] Reply to this message...        Jon Skeet [C# MVP] (VIP) Joel <Click here to reveal e-mail address> wrote: [Original message clipped] I'd suggest having either an abstract or empty method which is virtual, and make every method you want to call from your code non-virtual. It's fairly common to have a non-virtual method which does something (preparation, for example), calls a virtual or abstract method, and then does something else (clean-up or whatever). The non-virtual method is often public, with the abstract/virtual method being just protected. -- Jon Skeet - <Click here to reveal e-mail address> http://www.pobox.com/~skeet If replying to the group, please do not mail me too Reply to this message...        Joel That's the first thing I tried and it doesn't work. Check out http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csspec/html/vclrfcsharpspec_10_5_4.asp. Specifically the paragraph right after the first example. It explicity states: Had the invocation in B been written ((A)this).PrintFields(), it would recursively invoke the PrintFields method declared in B, not the one declared in A, since PrintFields is virtual and the run-time type of ((A)this) is B. I worked around my immediate problem but now I'm just academically curious. It doesn't strike me that there's anything "illegal" about doing what I want, it just seems like there is no syntax for it. Anyone from MS want to pitch in? </joel> "Luc E. Mistiaen" <Click here to reveal e-mail address> wrote in message news:Click here to reveal e-mail address... [Original message clipped] Reply to this message...        Brian Tyler It actually is possible at the IL level - using the CALL instruction versus the CALLVIRT. I am not sure why there doesn't seem to be a C# syntax for it. In my situation, I created a utility class in IL that I then merged in with my assembly (multi-module assembly). Unfortunately, VS.NET doesn't give you much help in such a build - makefiles are much easier. "Joel" <Click here to reveal e-mail address> wrote in message news:%Click here to reveal e-mail address... [Original message clipped] Reply to this message...        Microsoft I guess I'll have to start learning IL :-) Thanks for the info. I hope MS adds this to C# soon. It doesn't come up often but when you need it, you end up with a messy work-around. Thanks again. </joel> "Brian Tyler" <Click here to reveal e-mail address> wrote in message news:OT2s8$Click here to reveal e-mail address... > It actually is possible at the IL level - using the CALL instruction versus > the CALLVIRT. I am not sure why there doesn't seem to be a C# syntax for it. > In my situation, I created a utility class in IL that I then merged in with > my assembly (multi-module assembly). Unfortunately, VS.NET doesn't give you [Original message clipped] Reply to this message...        Ben Schwehn Microsoft wrote: [Original message clipped] Or use MC++ / C++/CLI. This language supports it. I guess changing languages just for one feature would be a bit of an overreaction, but since you consider learning IL anyways... ;) hth -- Ben http://bschwehn.de Reply to this message...        Luc E. Mistiaen The best I can think of then is: using System; namespace ConsoleApplication4 { class Class1 { [STAThread] static void Main(string[] args) { Derived d=new Derived(); d.Method1(); } } class Base { private void BaseMethod1() { Console.WriteLine("Base.Method1"); } public virtual void Method1() { BaseMethod1(); } public virtual void Method2() { Console.WriteLine("Base.Method2"); BaseMethod1(); } } class Derived : Base { public override void Method1() { Console.WriteLine("Derived.Method1"); base.Method2(); } } } Reply to this message...        russ I'm surprised that no one mentioned MyClass in VB.NET, which does exactly what you are asking about. It behaves as a me reference (this), except as if all the methods were NotOverridable (non-virtual) on the base class. And by searching Google for "MyClass equivalent C#", you are led to this: http://blogs.msdn.com/csharpfaq/archive/2004/03/12/88476.aspx Which explains that C# doesn't support anything like MyClass. -- russ "Joel" <Click here to reveal e-mail address> wrote in message news:Click here to reveal e-mail address... [Original message clipped] Reply to this message...     System.Console Ad MBR BootFX Best-of-breed application framework for .NET projects, developed by Matthew Baxter-Reynolds and MBR IT

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