C#•2y ago

❔ Call base method in multiple inheritance

Example of what i have:

public class A
{
  public virtual void Foo()
  {
    Console.Write("Hello ");
  }
}

public class B : A
{
  public override void Foo()
  {
    Console.Write("World");
    base.Foo();
  }
}

public class C : B
{
  public override void Foo()
  {
    Console.Write("!");
    base.Foo();
  }
}

public class A
{
  public virtual void Foo()
  {
    Console.Write("Hello ");
  }
}

public class B : A
{
  public override void Foo()
  {
    Console.Write("World");
    base.Foo();
  }
}

public class C : B
{
  public override void Foo()
  {
    Console.Write("!");
    base.Foo();
  }
}

When i call C#Foo() i get "Hello World!" but i only want to call the base method of A so my console result would be "Hello !" I hope you guys can understand what i want. How can i doing this

35 Replies

Kouhai•2y ago

You can't do that

KleidukosOP•2y ago

Okay

Kouhai•2y ago

What you basically want is something like base.base.Foo(), right? Unfortunately it's not possible

KleidukosOP•2y ago

Yeah, i mean something like that Maybe with reflection ?

Kouhai•2y ago

It's possible with reflection, but at this point the question would be why do that?

cap5lut•2y ago

the only thing that comes to mind would be to extract it as protected non virtual method to call it later in C

public class A
{
  public virtual void Foo()
  {
    FooCore();
  }

  protected FooCore()
  {
    Console.Write("Hellow");
  }
}
// B stays as in ur example
public class C : B
{
  public override void Foo()
  {
    FooCore();
  }
}

public class A
{
  public virtual void Foo()
  {
    FooCore();
  }

  protected FooCore()
  {
    Console.Write("Hellow");
  }
}
// B stays as in ur example
public class C : B
{
  public override void Foo()
  {
    FooCore();
  }
}

KleidukosOP•2y ago

I want to override OnClick() from WPF Button which is already overrwriten in a framework i use, but i have to use the button because its the NavigationViewItem from WPF UI Sorry i cant do that because i have no access to the framework

DeliBey•2y ago

You need to pass as a parent

Kouhai•2y ago

OnClick? Why do you want to override it?

KleidukosOP•2y ago

I dont want to use the WPF UI navigation, i want to use my own, because wpf ui dont support multiple pages of the same type with there same instance

Kouhai•2y ago

I guess at this point your only solution is reflection, or extending WPF without the additional framework on top of it

KleidukosOP•2y ago

private void OnClickReflection()
{
  var type = typeof(ButtonBase);

  const BindingFlags flags = BindingFlags.Instance | BindingFlags.InvokeMethod;
        
  var method = type.GetMethod("OnClick", flags);

  method?.Invoke(this, null);
}

private void OnClickReflection()
{
  var type = typeof(ButtonBase);

  const BindingFlags flags = BindingFlags.Instance | BindingFlags.InvokeMethod;
        
  var method = type.GetMethod("OnClick", flags);

  method?.Invoke(this, null);
}

Works perfectly

Aaron•2y ago

that still invokes it virtually

KleidukosOP•2y ago

What does that mean ?

MODiX•2y ago

Aaron

REPL Result: Success

public class A
{
    public virtual void Test()
    {
        Console.WriteLine("base class");
    }
}

public class B : A
{
    public override void Test()
    {
        Console.WriteLine("derived class");
    }
}

typeof(A).GetMethod("Test").Invoke(new B(), null);

public class A
{
    public virtual void Test()
    {
        Console.WriteLine("base class");
    }
}

public class B : A
{
    public override void Test()
    {
        Console.WriteLine("derived class");
    }
}

typeof(A).GetMethod("Test").Invoke(new B(), null);

Console Output

derived class

derived class

Quoted by

<@270457259065081856> from #void-spam (click here)

Compile: 499.563ms | Execution: 96.666ms | React with ❌ to remove this embed.

Aaron•2y ago

it still calls the version in the derived class

KleidukosOP•2y ago

But it works I think this is because i use the type of ButtonBase and NavigationViewItem extends from it.

Aaron•2y ago

I did the same thing there I used A as the type for reflection, which B derives from

KleidukosOP•2y ago

How can i use MODiX ?

Aaron•2y ago

$eval

MODiX•2y ago

To compile C# code in Discord, use !eval Example:

!eval for(int i = 0; i < 4; i++) Console.WriteLine(i);

!eval for(int i = 0; i < 4; i++) Console.WriteLine(i);

Please don't try breaking the REPL service. Also, remember to do so in #bot-spam!

MODiX•2y ago

Kleidukos

REPL Result: Success

public class A
{
  public virtual void Foo()
  {
    Console.Write("Hello ");
  }
}

public class B : A
{
  public override void Foo()
  {
    Console.Write("World");
    base.Foo();
  }
}

public class C : B
{
  public override void Foo()
  {
    Console.Write("!");
  }
}

        var type = typeof(A);

        const BindingFlags flags = BindingFlags.Instance | BindingFlags.InvokeMethod;

        var method = type.GetMethod("Foo", flags);

        method?.Invoke(new C(), null);

public class A
{
  public virtual void Foo()
  {
    Console.Write("Hello ");
  }
}

public class B : A
{
  public override void Foo()
  {
    Console.Write("World");
    base.Foo();
  }
}

public class C : B
{
  public override void Foo()
  {
    Console.Write("!");
  }
}

        var type = typeof(A);

        const BindingFlags flags = BindingFlags.Instance | BindingFlags.InvokeMethod;

        var method = type.GetMethod("Foo", flags);

        method?.Invoke(new C(), null);

Compile: 722.838ms | Execution: 98.919ms | React with ❌ to remove this embed.

KleidukosOP•2y ago

Oh, i forgot the result...

Kouhai•2y ago

This won't even work, you need BindingFlags.Public as well and as antiwraith said it's still a virtual call I believe you'd need to get a function pointer to it typeof(A).GetMethod("Foo").MethodHandle.GetFunctionPointer(); something like that

Aaron•2y ago

Kouhai•2y ago

Need the public bindingflag BindingFlags.Public

Aaron•2y ago

oh I added Instance again lmao

MODiX•2y ago

Aaron

REPL Result: Success

public class A
{
  public virtual void Foo()
  {
    Console.WriteLine("Hello ");
  }
}

public class B : A
{
  public override void Foo()
  {
    Console.WriteLine("World");
    base.Foo();
  }
}

public class C : B
{
  public override void Foo()
  {
    Console.WriteLine("!");
  }
}

        var type = typeof(A);

        const BindingFlags flags = BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.Public;

        var method = type.GetMethod("Foo", flags);

        method?.Invoke(new C(), null);

public class A
{
  public virtual void Foo()
  {
    Console.WriteLine("Hello ");
  }
}

public class B : A
{
  public override void Foo()
  {
    Console.WriteLine("World");
    base.Foo();
  }
}

public class C : B
{
  public override void Foo()
  {
    Console.WriteLine("!");
  }
}

        var type = typeof(A);

        const BindingFlags flags = BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.Public;

        var method = type.GetMethod("Foo", flags);

        method?.Invoke(new C(), null);

Console Output

Compile: 718.116ms | Execution: 87.091ms | React with ❌ to remove this embed.

Aaron•2y ago

yeah there

DeliBey•2y ago

Are we trying to output "!" ?

Aaron•2y ago

trying to get Hello

KleidukosOP•2y ago

In my app it works, why not here

KleidukosOP•2y ago

I dont understand why it works in my project (Not the example) Here a screen from my code

KleidukosOP•2y ago

And i checked, method is not null

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Call base method in multiple inheritance

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