Question

I’m using a library that generates a bunch of classes for me.

These classes all inherit from a common base class but that base class doesn’t define a couple methods that are common to all subclasses.

For example:

SubClassA : BaseClass{   void Add(ItemA item) {...}   ItemA CreateNewItem() {...} }  SubClassB: BaseClass{   void Add(ItemB item) {...}   ItemB CreateNewItem() {...} } 

Unfortunately, the base class doesn’t have these methods. This would be great:

BaseClass{   // these aren't actually here, I'm just showing what's missing:   abstract void Add(ItemBaseClass item);  // not present!   abstract ItemBaseClass CreateNewItem(); // not present! } 

Since there is a common base class for my A+B objects and a common base class for the Item objects, I had hoped to benefit from the wonderful world of polymorphism.

Unfortunately, since the common methods aren’t actually present in the base class, I can’t call them virtually. e.g., this would be perfect:

BaseClass Obj; Obj = GetWorkUnit(); // could be SubClassA or SubClassB  ItemBaseClass Item = Obj.CreateNewItem(); // Compile Fail: CreateNewItem() isn't in the base class  Item.DoSomething();  Obj.Add(Item); // Compile Fail: Add(...) isn't in the base class 

Obviously casting would work but then I’d need to know which type I had which would negate the benefits.

How can I ‘force’ a call to these methods? I’m not worried about getting an object that doesn’t implement the method I’m trying to call. I can actually do what I want in VB–I don’t get intellisense but the compiler’s happy and it works:

CType(Obj, Object).Add(Item) // Note: I'm using C#--NOT VB 

Againt, I have no control over these classes (which I think rules out partial classes).

Answer 1

You cannot call a non-virtual method of a derived class without resorting to reflection or other dirty tricks. If you want to do it, it’s easy then:

// obj is your object reference. obj.GetType().InvokeMember('MethodName',      System.Reflection.BindingFlags.InvokeMethod, null, obj, null /* args */)