Custom Collections.md

Custom Collections

Simple Explanation

Custom collections in C# and .NET allow developers to create collections that meet specific requirements and use cases that are not met by the built-in collections provided by the framework. These collections can be tailored to meet specific performance, memory, and functionality requirements and can be used in a wide range of applications.

Deep Explanation

Custom collections are classes that implement one or more of the collection interfaces provided by the .NET framework, such as ICollection, IList, IDictionary, or IEnumerable. These interfaces define the basic operations that a collection can perform, such as adding, removing, and accessing items. By implementing these interfaces, custom collections can be used in a similar way to the built-in collections provided by the framework, with the added benefit of having specific requirements and use cases met.

Custom collections can be created for a wide range of scenarios, such as high-performance scenarios, scenarios that require thread safety, scenarios that require custom serialization and deserialization, and scenarios that require custom indexing or sorting. The implementation of a custom collection depends on the specific requirements of the scenario, but can include optimizations such as using arrays instead of lists for better performance, implementing thread-safe locks, and using custom comparison or sorting algorithms.

Examples

Custom List implementation:

public class MyList<T> : IList<T>
{
    private List<T> innerList = new List<T>();

    public T this[int index]
    {
        get { return innerList[index]; }
        set { innerList[index] = value; }
    }

    public int Count => innerList.Count;

    public bool IsReadOnly => false;

    public void Add(T item)
    {
        innerList.Add(item);
    }

    // Other IList implementation methods...
}

Custom Dictionary implementation:

public class MyDictionary<TKey, TValue> : IDictionary<TKey, TValue>
{
    private Dictionary<TKey, TValue> innerDictionary = new Dictionary<TKey, TValue>();

    public TValue this[TKey key]
    {
        get { return innerDictionary[key]; }
        set { innerDictionary[key] = value; }
    }

    public int Count => innerDictionary.Count;

    public bool IsReadOnly => false;

    public ICollection<TKey> Keys => innerDictionary.Keys;

    public ICollection<TValue> Values => innerDictionary.Values;

    public void Add(TKey key, TValue value)
    {
        innerDictionary.Add(key, value);
    }

    // Other IDictionary implementation methods...
}