You can create extension methods to improve usability for nested collections like a Dictionary with a List<T> value.
Consider the following extension methods:
public static class DictListExtensions
{
public static void Add<TKey, TValue, TCollection>(this Dictionary<TKey, TCollection> dict, TKey key, TValue value)
where TCollection : ICollection<TValue>, new()
{
TCollection list;
if (!dict.TryGetValue(key, out list))
{
list = new TCollection();
dict.Add(key, list);
}
list.Add(value);
}
public static bool Remove<TKey, TValue, TCollection>(this Dictionary<TKey, TCollection> dict, TKey key, TValue value)
where TCollection : ICollection<TValue>
{
TCollection list;
if (!dict.TryGetValue(key, out list))
{
return false;
}
var ret = list.Remove(value);
if (list.Count == 0)
{
dict.Remove(key);
}
return ret;
}
}you can use the extension methods as follows:
var dictList = new Dictionary<string, List<int>>();
dictList.Add("example", 5);
dictList.Add("example", 10);
dictList.Add("example", 15);
Console.WriteLine(String.Join(", ", dictList["example"])); // 5, 10, 15
dictList.Remove("example", 5);
dictList.Remove("example", 10);
Console.WriteLine(String.Join(", ", dictList["example"])); // 15
dictList.Remove("example", 15);
Console.WriteLine(dictList.ContainsKey("example")); // False