How to call base method from derived class instance in C#?

c#, inheritance

Solution

There is no way to access base method from outside the derived class. You can either write a method in derived class that will call base method like this:

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

    public void basePrint() { base.print(); }
}

Or you can user `Reflection` to get base method definition and invoke it but it's rather ugly. Here is how to create `DynamicMethod` that calls base `print` method:

// Get MethodInfo of the base method
var methodInfo = typeof(A).GetMethod("Print", BindingFlags.Instance | BindingFlags.Public);

// Create DynamicMethod based on the methodInfo
var dynamicMethod = new DynamicMethod("BasePrint", methodInfo.ReturnType, new[] { methodInfo.DeclaringType }, methodInfo.DeclaringType);
// Create ILGenerator for the dynamic method
var il = dynamicMethod.GetILGenerator();

// Emit argument with index 0 - DeclaringType
il.Emit(OpCodes.Ldarg_0);
// Emit method call
il.EmitCall(OpCodes.Call, methodInfo, null);
// Emit method return value
il.Emit(OpCodes.Ret);

// Invoke method with target...
var b = new B();
dynamicMethod.Invoke(null, new object[] {b});

// ... or create a delegate and invoke method without target
var action = dynamicMethod.CreateDelegate(typeof(Action)) as Action;
action.Invoke();

Note that it'll work only for parameterless method. If you want to call method with parameters you'll have to put their types into the array with the `DeclaringType` and later emit all of them. Also you'll have to create delegate of type `Action<parameterTypes` or `Func<returnType, parameterTypes>` if the method returns something.

Problem

Original source

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