Only create dictionary once - and use that when dictionary is being called?-CodePudding

I am currently working on refactoring some code, where I have stumbled upon this static dictionary:

public static Dictionary<string, string> CountryNamesAndCodes()
{
    var dictionary = new Dictionary<string, string>();
   
    dictionary.Add("AF", "Afghanistan");
    dictionary.Add("AL", "Albania");
    dictionary.Add("DZ", "Algeria");
    dictionary.Add("AD", "Andorra");
    dictionary.Add("AO", "Angola");
    dictionary.Add("AG", "Antigua and Barbuda");
    dictionary.Add("AR", "Argentina");
    dictionary.Add("AM", "Armenia");
    ...
}

Which first of all is defined in the service layer, and takes up a lot a space - 400 lines, and eventhough it is static, it seem to always recreate the dictionary, meaning making the static part of it redundant - or am I wrong?

how do I ensure that this is only created once, and everytime I call it, it make use of the same instance.

CodePudding user response：

You are quite right, you can extract the local dictionary as a static member

I suggest something like this (field):

// static readonly (we want to create it once) field of
// IReadOnlyDictionary type - we want to read key value pairs after its creation 
private static readonly IReadOnlyDictionary<string, string> countries = 
  // We may want to be nice and let ignore case for keys  
  new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase) {
    { "AF", "Afghanistan" },
    { "AL", "Albania" },
    { "DZ", "Algeria" },
    //TODO:Put all the other records here    
  };

or like this (property):

// static readonly (there's no "set") property of
// IReadOnlyDictionary type - we want just to read key value pairs after its creation 
private static IReadOnlyDictionary<string, string> Countries { get; } = 
  new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase) {
    { "AF", "Afghanistan" },
    { "AL", "Albania" },
    { "DZ", "Algeria" },
    //TODO:Put all the other records here
};

CodePudding user response：

public static class Globals
{
    static Dictionary<string, string> 
    CountryNamesAndCodes = new Dictionary<string, string>
    {   
        {"AF", "Afghanistan"},
        {"AL", "Albania"}
    };
}

name = Globals.CountryNamesAndCodes["AF"];