DictionaryListTKey, TValue Class

public class DictionaryList<TKey, TValue> : IList<KeyValuePair<TKey, TValue>>, 
	ICollection<KeyValuePair<TKey, TValue>>, IEnumerable<KeyValuePair<TKey, TValue>>, 
	IEnumerable, IDictionary<TKey, TValue>

Public Class DictionaryList(Of TKey, TValue)
	Implements IList(Of KeyValuePair(Of TKey, TValue)), 
	ICollection(Of KeyValuePair(Of TKey, TValue)), IEnumerable(Of KeyValuePair(Of TKey, TValue)), 
	IEnumerable, IDictionary(Of TKey, TValue)

generic<typename TKey, typename TValue>
public ref class DictionaryList : IList<KeyValuePair<TKey, TValue>>, 
	ICollection<KeyValuePair<TKey, TValue>>, IEnumerable<KeyValuePair<TKey, TValue>>, 
	IEnumerable, IDictionary<TKey, TValue>

type DictionaryList<'TKey, 'TValue> = 
    class
        interface IList<KeyValuePair<'TKey, 'TValue>>
        interface ICollection<KeyValuePair<'TKey, 'TValue>>
        interface IEnumerable<KeyValuePair<'TKey, 'TValue>>
        interface IEnumerable
        interface IDictionary<'TKey, 'TValue>
    end

JavaScript does not support generic types or methods.

Type Parameters

TKey

Generic key type.

TValue

Generic value type.

Have you ever needed the quick look-up feature on a Dictionary (e.g., Hashtable), but ended up missing the indexed or sequential access like you have in a list? You may have wondered why the .NET dictionary class doesn’t implement the IList interface which allows this. The reason IDictionary implementations do not normally implement the IList interface is because of ambiguity that is caused when implementing an integer key. For example, if you created a dictionary style class with a key of type "Integer" that actually did implement IList(Of T), you would not be able to access items in the IList interface by index without "casting" the class as IList. This is because the Item property in both the IDictionary and IList would have the same parameters. Note, however, that generics in .NET 2.0 gladly allow a class to implement both IDictionary and IList (even specifying as Integer as the key) so long you as you are happy knowing that the compiler will choose if you access your items by index or key. Given that caveat, there are many times when you need a dictionary style collection but also desire an IList implementation so the class can be used in other ways without conversion. As a result of these needs, we’ve added a generic class to code library called a DictionaryList -- which is essentially just a sorted dictionary style list (i.e., SortedList) that implements the IList(Of T) interface (specifically as IList(Of KeyValuePair(Of TKey, TValue))). You will find all of your convenient expected methods related to both dictionaries and lists; that is, you can look-up items by key or by index. The class works perfectly for any non-Integer based key (e.g., String, custom class, etc.) -- note that specifying an Integer as the key for the class won’t cause an error, but it also will not be very useful. However, you can specify the key for your DictionaryList as a "Long," which allows you to use long integers for keyed look-ups and regular integers for indexed access--the best of both worlds! In summary, I would not change your programming habits to start using this for "my collection for everything," as nothing comes for free; however, if you have a need for a "hybrid" collection class, this fits the bill.

Important note about using an "Integer" as the key for this class: IDictionary implementations do not normally implement the IList interface because of ambiguity that is caused when implementing an integer key. For example, if you implement this class with a key of type "Integer" you will not be able to access items in the queue by index without "casting" the class as IList. This is because the Item property in both the IDictionary and IList would have the same parameters.

Note that prior to the addition of Generics in .NET, the class that performed a similar function was the "NameObjectCollectionBase" in the System.Collections.Specialized namespace which specifically allowed item access by either key or by index. This class is similar in function but instead is a generic class allowing use with any strongly typed key or value.

Reference