Polly in base class execute abstract method with paramter

Question

I'm trying to add Polly policy in a base class. The problem is that the method I want to retry is an abstract method with a parameter, and the children classes define that parameter. Code sample:

public abstract class BaseClass
{   
    protected BaseClass()
    {
        // original code
        // someEvent += OnChange;
        someEvent += OnChangeBase;      
    }

    private void OnChangeBase()
    {
        var policy = GetRetryPolicy();
        // how do I use the bool parameter from children class?
        policy.Execute(() => OnChange(??));
    }

    protected abstract void OnChange(bool param);
}

How do I achieve this?

Answer 1

This can be solved with standard abstract class patterns. The solution isn't particularly different because Polly is involved.

You could just add to the base class:

protected abstract bool GetBoolParameterValue(); // choose a name more meaningful to your use case

And then the code line executing through the policy becomes:

policy.Execute(() => OnChange(GetBoolParameterValue()));

This uses an abstract method, but you could also use an abstract property; or a bool field defined on the base class.

---

Alternatively: The question presents that the signature of OnChangeBase is OnChangeBase(). But if the original signature of OnChange was OnChange(bool), can you just do this?

public abstract class BaseClass
{   
    protected BaseClass()
    {
        // original code
        // someEvent += OnChange;
        someEvent += OnChangeBase;      
    }

    private void OnChangeBase(bool foo)
    {
        var policy = GetRetryPolicy();
        policy.Execute(() => OnChange(foo));
    }

    protected abstract void OnChange(bool param);
}