AddToList
Given a dictionary where the value type is a List, add items to values of the dictionary, and/or create a list of items as needed, without having to test if the key item already exists.
Source
public static void AddToList<T, K>(this IDictionary<T, HashSet<K>> store, T key, K item)
{
if (!store.TryGetValue(key, out var value))
{
value = new HashSet<K>();
store[key] = value;
}
value.Add(item);
}
public static void AddToList<T, K>(this IDictionary<T, List<K>> store, T key, K item)
{
if (!store.TryGetValue(key, out var value))
{
value = new List<K>();
store[key] = value;
}
value.Add(item);
}
Example
Dictionary<int, List<string>> carNamesByManufacturerId = new Dictionary<int, List<string>>();
var honda = 1;
var ford = 2;
carNamesByManufacturerId.AddToList(honda, "Accord");
carNamesByManufacturerId.AddtoList(honda, "CRX");
carNamesByManufacturerId.AddToList(ford, "Focus");
carNamesByManufacturerId.AddToList(ford, "Edge");
//without extension method (old way)
if (!carNamesByManufacturerId.TryGetValue(ford, out fords))
{
fords = new List<string>();
carNamesByManufacturerId[ford] = fords;
}
fords.Add("Edge");
Author: Eric Robishaw
Submitted on: 23 okt. 2020
Language: csharp
Type: System.Collections.Generic.IDictionary
Views: 3464