Backward Compatibility in Practice with C#

using System;
using System.Collections.Generic;

class DataProcessor
{
    public void ProcessData(List<Dictionary<string, object>> items)
    {
        List<Dictionary<string, object>> processedItems = new List<Dictionary<string, object>>();
        foreach (var item in items)
        {
            Dictionary<string, object> processedItem = new Dictionary<string, object>();
            foreach (var entry in item)
            {
                if (entry.Value is string)
                {
                    processedItem[entry.Key] = ((string)entry.Value).ToUpper();
                }
                else
                {
                    processedItem[entry.Key] = entry.Value;
                }
            }
            processedItems.Add(processedItem);
        }
        for (int i = 0; i < Math.Min(3, processedItems.Count); i++)
        {
            Console.WriteLine("Processed Item: " + processedItems[i]);
        }
    }
}

using System;
using System.Collections.Generic;

class DataProcessor
{
    public void ProcessData(List<Dictionary<string, object>> items)
    {
        ProcessData(items, item => true, null);
    }

    public void ProcessData(List<Dictionary<string, object>> items, Func<Dictionary<string, object>, Dictionary<string, object>> transform)
    {
        ProcessData(items, item => true, transform);
    }

    public void ProcessData(List<Dictionary<string, object>> items, Predicate<Dictionary<string, object>> condition, Func<Dictionary<string, object>, Dictionary<string, object>> transform)
    {
        List<Dictionary<string, object>> processedItems = new List<Dictionary<string, object>>();
        foreach (var item in items)
        {
            if (condition(item))  // Apply condition to filter items
            {
                Dictionary<string, object> processedItem;
                if (transform != null)
                {
                    processedItem = transform(item);  // Apply custom transformation if provided
                }
                else
                {
                    // Default transformation: Convert string values to uppercase
                    processedItem = new Dictionary<string, object>();
                    foreach (var entry in item)
                    {
                        if (entry.Value is string)
                        {
                            processedItem[entry.Key] = ((string)entry.Value).ToUpper();
                        }
                        else
                        {
                            processedItem[entry.Key] = entry.Value;
                        }
                    }
                }
                processedItems.Add(processedItem);
            }
        }
        for (int i = 0; i < Math.Min(3, processedItems.Count); i++)
        {
            Console.WriteLine("Processed Item: " + processedItems[i]);
        }
    }
}

// Usage examples:
class Program
{
    static void Main(string[] args)
    {
        List<Dictionary<string, object>> data = new List<Dictionary<string, object>>();
        Dictionary<string, object> item1 = new Dictionary<string, object>
        {
            { "name", "apple" },
            { "quantity", 10 }
        };
        data.Add(item1);
        Dictionary<string, object> item2 = new Dictionary<string, object>
        {
            { "name", "orange" },
            { "quantity", 5 }
        };
        data.Add(item2);

        DataProcessor processor = new DataProcessor();

        // Default behavior - convert string values to uppercase
        processor.ProcessData(data);

        // Custom filter - select items with a quantity greater than 5
        processor.ProcessData(data, item => (int)item["quantity"] > 5, null);

        // Custom transformation - convert names to uppercase and multiply the quantity by 2
        processor.ProcessData(data, item =>
        {
            Dictionary<string, object> transformed = new Dictionary<string, object>();
            foreach (var entry in item)
            {
                if (entry.Key.Equals("name"))
                {
                    transformed[entry.Key] = ((string)entry.Value).ToUpper();
                }
                else
                {
                    transformed[entry.Key] = (int)entry.Value * 2;
                }
            }
            return transformed;
        });
    }
}