Solving the 'Virtual method call in constructor' issue

Question

I am making a software in c#. I am using an abstract class, Instruction, that has these bits of code:

protected Instruction(InstructionSet instr         


        

Answer 1

When you create an instance of your derived class, your call stack will look like this:

GetRealInstruction()
BaseContructor()
DerivedConstructor()

GetRealInstruction is overridden in the derived class, whose constructor has not finished running yet.

I don't know how your other code looks, but you should first check if you really needed a member variable in this case. You have a method that returns the object you need. If you really do need it, make a property and call GetRealInstruction() in the getter.

Also you can make GetRealInstruction abstract. That way you don't have to throw the exception and compiler will give you an error if you forget to override it in a derived class.