Solving virtual member call in constructor

Question

I have an abstract class:

public abstract class ExampleBase : IExampleBase
{
    protected ExampleBase() 
    {
        this.SetupData();
    }

    protected abstract Dictionary<int, Adress> RelevantData { get; set; }

    protected abstract void SetupData();

    public void ProcessData() 
    {
        // use RelevantData
    }
}

And a derived class:

public class Example : ExampleBase
{
    public Example()
    {
    }

    protected override void SetupData()
    {
        this.RelevantData = new Dictionary<int, Adress>
        { 1, new Adress { ... } },
        { 2, new Adress { ... } }
    }
}

In the base class, ReSharper tells me

Virtual member call in constructor

I understand that it's dangerous to call the method because of the execution order.. but how can I resolve this issue?

Context: I want to set up data in each derived class which will then be processed in the base class. I wanted to call the SetupData() method in the base class since it's the same in every derived class.

Derived class:

• Set up the data

Base class:

• Process the data

Answer 1

You don't. You accept the fact this is dangerous, and (try to) prevent this. This is a design flaw!

You could prevent this for example by moving the call to the highest level class, or make every class responsible for it's own, thus removing the unsafe part of the method call. Then you don't need another class (a base class) to take responsibility for its deriving classes.

If that isn't possible. Make very clear using comments or any other method available that the developer should take this problem into account when updating the code.