Duct-typed extension methods Example 7

Example7.cs

// 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 },
  { "Germany", 81_914_672 },
  { "United Kingdom", 65_788_574 }
};

// This is the dictionary spread method
public static void Add<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, IDictionary<TKey, TValue> items)
{
  foreach (var item in items)
  {
    dictionary[item.Key] = item.Value;
  }
}

// It makes this possible
var populations = new Dictionary<string, int>
{
  { "China", 1_409_517_397 },
  { "India", 1_339_180_127 },
  { "USA", 324_459_463 },
  { "Indonesia", 263_991_379 },
  { "Brazil", 209_288_278 },
  GetAfricanCountries(),
  GetEuropeanCountries()
};

// Output each item, to see if things work correctly
foreach(var (key, value) in populations)
{
  Console.WriteLine($"{key}: {value}");
}