mariusGundersen

// Example 11: add with params

// Use params to take several ints, each representing 3 digits
public static void Add<TKey>(this IDictionary<TKey, int> dictionary, TKey key, params int[] values)
=> dictionary.Add(key, values.Aggregate(0, (s, v) => s*1000 + v));

// Now we can write it like this
var populations = new Dictionary<string, int>
{
  { "China", 1,409,517,397 },

mariusGundersen

// Example 10: add a tuple

// This is just a dummy class that we can use in the example
public class City
{
  public City(string name, int population, string country)
  {
    Name = name;
    Population = population;
    Country = country;

mariusGundersen

// Example 9: multi or single dimensional arrays?

// We define this extension method
public static void Add<T>(this List<T> list, params T[] items)
=> list.AddRange(items);

// And then we can make a flattened matrix
var matrix = new List<double>
{
  { 1, 0, 0 },

mariusGundersen

// Example 8: add a new instance

// This is just a dummy class that we can use in the example
public class City
{
  public City(string name, int population, string country)
  {
    Name = name;
    Population = population;
    Country = country;

mariusGundersen

// Example 7: add a dictionary

// These are just some dummy methods for the example to work
public static IDictionary<string, int> GetAfricanCountries() => new Dictionary<string, int>{
  { "Nigeria", 190_886_311 },
  { "Ethiopia", 104_957_438 },
  { "Egypt", 97_553_151 }
};
public static IDictionary<string, int> GetEuropeanCountries() => new Dictionary<string, int>{
  { "Russia", 146_864_513 },

mariusGundersen

// Example 6: Add a list

// This is just a dummy method that returns some ints
public static IEnumerable<int> GetAnotherListOfInts() 
=> new[] { 10, 11, 12, 13 };

// With this extension method...
public static void Add<T>(this List<T> list, IEnumerable<T> items)
=> list.AddRange(items);

mariusGundersen

using System.Runtime.CompilerServices;
using System.Threading.Tasks;

// Example 5: await tuple of Tasks

// Just some dummy async functions
public static Task<string> GetSomethingAsync(int number) => Task.FromResult($"Something {number}");
public static Task<int> GetAnotherThingAsync(string text) => Task.FromResult(text.Length);

// This extension method lets us await a tuple with two values

mariusGundersen

using System.Runtime.CompilerServices;
using System.Threading.Tasks;

// Example 4: await IEnumerable<Task<T>>

// Just a dummy async function
public static Task<string> GetSomethingAsync(int number) => Task.FromResult($"Something {number}");

// This extension method allows us to await many tasks
public static TaskAwaiter<T[]> GetAwaiter<T>(this IEnumerable<Task<T>> manyTasks)

mariusGundersen

using System.Runtime.CompilerServices;
using System.Threading.Tasks;

// Example 3: await Lazy<Task<T>>

// Just a dummy async function
public static Task<string> GetSomethingAsync(int number) => Task.FromResult($"Something {number}");

// We need a lazy variable to work with
var lazySomething = new Lazy<Task<string>>(() => GetSomethingAsync(10));

mariusGundersen

using System.Runtime.CompilerServices;
using System.Threading.Tasks;

// Example 2: await anything
public static TaskAwaiter<T> GetAwaiter<T>(this T nonAwaitable)
=> Task.FromResult(nonAwaitable).GetAwaiter();

// Now we can write code like this
await "Hello world";
await 100;