C#

var dataSourceName = (
                                                      from entry in entityParams

                                                      where entry is KeyValuePair<string, string> && entry != null && ((KeyValuePair<string, string>)entry).Key.Equals("DataSourceName")
                                                      select ((KeyValuePair<string, string>)entry).Value).FirstOrDefault();

using SwitchKing.Common.Entities;

public class MarketData
    {
        #region "Private Data Members"
        private int _countAdvanceCurve;       
        private int _countAdvancesSBCAgencyCurve;
        private int _countAdvancesSBCAAACurve;
        private int _countFhlbsfTreasuryCurve;
        private int _countDNCOCurve;  
        #endregion "Private Data Members"
        #region "Public Data Members"
        public int CountAdvanceCurve
        {
            get { return _countAdvanceCurve; }
            set { _countAdvanceCurve = value; }
        }
}

public abstract class BaseClass
{
    private int id;
        
    // CA2214 Do not call overridable methods in constructors
    protected BaseClass()
    {
        Initialize(out id); // Initialize derived class with it's own specific data and get common data back here for initialization
    }

    public int Id { get { return id; } }

    protected abstract void Initialize(out int id);
}
public class ConcreteA : BaseClass
{
    public ConcreteA()
        : base()
    { }

    protected override void Initialize(out int id)
    {
        ConcreteAIntializationData data = NativeMethods.ConcreteAInitialize();
        id = data.Id;
    }
}
public class ConcreteB : BaseClass
{
    private string name;

    public ConcreteB()
        : base()
    { }

    protected override void Initialize(out int id)
    {
        ConcreteBIntializationData data = NativeMethods.ConcreteBInitialize();
        id = data.Id;
        name = data.name;
    }
}

public static class NativeMethods
{
    // In the real code this is an external C++ dll call
    public static ConcreteAIntializationData ConcreteAInitialize()
    {
        return new ConcreteAIntializationData();
    }
    // In the real code this is an external C++ dll call
    public static ConcreteBIntializationData ConcreteBInitialize()
    {
        return new ConcreteBIntializationData();
    }
}
// In the real code this is a C++ structure
public class ConcreteAIntializationData
{
    private int id;

    // In the real code this struct is filled by unmanaged code.
    public ConcreteAIntializationData()
    {
        id = 1;
    }

    public int Id
    {
        get { return id; }
    }
}
public class ConcreteBIntializationData
{
    private int id;
    public string name;

    // In the real code this struct is filled by unmanaged code.
    public ConcreteBIntializationData()
    {
        id = 2;
        name = "Name";
    }

    public int Id
    {
        get { return id; }
    }
    public string Name
    {
        get { return name; }
    }
}