Force method call in all derived classes

Question

I have base and derived classes:

public abstract class DataServiceBase {
  public abstract List<Data> GetData(String name);
}

public class DataService : DataServiceBase {
  public override List<Data> GetData(String name) {

     // GetData from API
     // Call Interceptor.Register(List<Data> data)
     return data;
  }
}

I would like the derived classes to call Interceptor.Register(List<Data> data) in GetData before returning the data.

Is there a way to make sure that this always happens?

What if you make `GetData` public and not virtual, and inside you call an internal abstract method GetDataInternal ? — Gerardo Grignoli, Apr 04 '22 at 17:53

score 1 · Answer 1 · answered Apr 04 '22 at 18:00

Yes, the template method pattern, as Alexander suggested. Here, we implement GetData in the abstract base class, which calls the GetDataInternal (for a lack of a better name) hook. The hook is implemented in each derived class and is called when you call GetData (which also calls your interception code).

public abstract class DataServiceBase
{
    public List<Data> GetData(String name)
    {
        var data = GetDataInternal(name);
        Interceptor.Register(data);
        return data;
    }

    internal abstract List<Data> GetDataInternal(String name);
}

public class DataService : DataServiceBase
{
    internal override List<Data> GetDataInternal(String name)
    {
        var data = new List<Data>();
        // GetData from API
        return data;
    }
}

Force method call in all derived classes

1 Answers1