FallbackCultureProvider

ILocalization.FallbackCultureProvider is a property (IProvider<string, string[]>) that determines which cultures are to be used for fallback when resource for requested culture is not found.

// Get culture provider
IProvider<string, string[]> fallbackCultureProvider = Localization.Default.FallbackCultureProvider;
// Retrieve fallback cultures
string[] fallbackCultures = fallbackCultureProvider["fi-FI"];
// Print fallback cultures in evaluation order
WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → ""

FallbackCultureProvider.Default provider returns following cultures:

• Requested culture
• Requested culture's parents
• Culture from application assembly's System.Resources.NeutralResourcesLanguageAttribute.
• Application's fallback culture parents
• Invariant culture ""

The default culture provider searches for System.Resources.NeutralResourcesLanguageAttribute from application assembly (not from class libraries).

[assembly: System.Resources.NeutralResourcesLanguageAttribute("en-UK")] 

If [NeutralResourcesLanguage] is detected, then its fallback cultures are also provided.

// Get culture provider
IProvider<string, string[]> fallbackCultureProvider = Localization.Default.FallbackCultureProvider;
// Retrieve fallback cultures
string[] fallbackCultures = fallbackCultureProvider["fi-FI"];
// Print fallback cultures in evaluation order
WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "en-UK" → "en" → ""

new FallbackCultureProvider(culture) creates culture provider that uses the specified fallback culture, or 'null' for none. It also returns invariant culture. This constructor does not use [NeutralResourcesLanguageAttribute].

// Create localization
ILocalization localization = new Localization()
    .SetFallbackCultureProvider(new FallbackCultureProvider("sv"));
// Get fallback cultures
string[] fallbackCultures = localization.FallbackCultureProvider["fi-FI"];
// Print fallback cultures in evaluation order
WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "sv" → ""

FallbackCultureProvider.Get(culture) gets or creates cached culture provider.

// Create localization
ILocalization localization = new Localization();
// Assign culture provider "en"
localization.FallbackCultureProvider = FallbackCultureProvider.Get("en");
// Get fallback cultures
string[] fallbackCultures = localization.FallbackCultureProvider["fi-FI"];
// Print fallback cultures in evaluation order
WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "en" → ""

FallbackCultureProvider.Invariant returns "" as fallback culture.

// Create localization
ILocalization localization = new Localization();
// Assign culture provider "en"
localization.FallbackCultureProvider = FallbackCultureProvider.Invariant;
// Get fallback cultures
string[] fallbackCultures = localization.FallbackCultureProvider["fi-FI"];
// Print fallback cultures in evaluation order
WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "en" → ""

Culture provider can be adapted from delegate.

// Create fallback provider function
Func<string, string[]> func = culture => new string[] { culture, "en", "" }.Distinct().ToArray();
// Create provider
IProvider<string, string[]> fallbackCultureProvider = Providers.Func(func).Cached();
// Get fallback cultures
string[] fallbackCultures = fallbackCultureProvider["fi"];
// Print fallback cultures in evaluation order
WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi" → "en" → ""

FallbackCultureProvider.NoFallback is provider that does not use fallback.

// Get culture provider
IProvider<string, string[]> fallbackCultureProvider = FallbackCultureProvider.NoFallback;
// Retrieve fallback cultures
string[] fallbackCultures = fallbackCultureProvider["fi-FI"];
// Print fallback cultures in evaluation order
WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI"

The localization.FallbackCultureProvider is applied to all the providers in the 'localization'.

// Create localization
ILocalization localization = new Localization()
    .SetFallbackCultureProvider(FallbackCultureProvider.Default)
    .AddLines(new LocalizationReaderYaml.File("fallbackcultureprovider/fallbackcultureprovider.yaml"));
// Get localizable text
ILocalizableText localizable = localization.LocalizableTextCached["Namespace.HelloCasual"];
// Cultures to print with
foreach (string requested_culture in new string[] { "en", "en-NZ", "en-AU", "en-UK", "en-US", "en-CA" })
{
    // Localize to culture
    ILocalizedText localized = localizable.Localize(requested_culture)?.Value!;
    // Get the culture where fallback landed to
    string supplied_culture = localized.Culture;
    // Print text
    WriteLine($"{requested_culture,-5} {supplied_culture,-5}: {localized.Print(null)}");
}
// en    en   : Hello fella
// en-NZ en   : Hello fella
// en-AU en-AU: Hello mate
// en-UK en-UK: Hello chap
// en-US en-US: Hello dude
// en-CA en-CA: Hello buddy

fallbackcultureprovider/fallbackcultureprovider.yaml [Demo]

TemplateFormat: Detect

Items:
- Key: Namespace.HelloCasual
  Items:
  - Text: "Hello fella"
    Culture: en
  - Text: "Hello mate"
    Culture: en-AU
  - Text: "Hello chap"
    Culture: en-UK
  - Text: "Hello dude"
    Culture: en-US
  - Text: "Hello buddy"
    Culture: en-CA

Full Example

Full example

using System.Globalization;
using Avalanche.Localization;
using Avalanche.Utilities.Provider;
using static System.Console;

class fallbackcultureprovider
{
    public static void Run()
    {        
        {
            // <01>
            // Get culture provider
            IProvider<string, string[]> fallbackCultureProvider = Localization.Default.FallbackCultureProvider;
            // Retrieve fallback cultures
            string[] fallbackCultures = fallbackCultureProvider["fi-FI"];
            // Print fallback cultures in evaluation order
            WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → ""
            // </01>
        }
        {
            // <02>
            // Get culture provider
            IProvider<string, string[]> fallbackCultureProvider = Localization.Default.FallbackCultureProvider;
            // Retrieve fallback cultures
            string[] fallbackCultures = fallbackCultureProvider["fi-FI"];
            // Print fallback cultures in evaluation order
            WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "en-UK" → "en" → ""
            // </02>
        }
        {
            // <03>
            // Create localization
            ILocalization localization = new Localization()
                .SetFallbackCultureProvider(new FallbackCultureProvider("sv"));
            // Get fallback cultures
            string[] fallbackCultures = localization.FallbackCultureProvider["fi-FI"];
            // Print fallback cultures in evaluation order
            WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "sv" → ""
            // </03>
        }
        {
            // <03A>
            // Create localization
            ILocalization localization = new Localization();
            // Assign culture provider "en"
            localization.FallbackCultureProvider = FallbackCultureProvider.Get("en");
            // Get fallback cultures
            string[] fallbackCultures = localization.FallbackCultureProvider["fi-FI"];
            // Print fallback cultures in evaluation order
            WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "en" → ""
            // </03A>
        }
        {
            // <03B>
            // Create localization
            ILocalization localization = new Localization();
            // Assign culture provider "en"
            localization.FallbackCultureProvider = FallbackCultureProvider.Invariant;
            // Get fallback cultures
            string[] fallbackCultures = localization.FallbackCultureProvider["fi-FI"];
            // Print fallback cultures in evaluation order
            WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI" → "fi" → "en" → ""
            // </03B>
        }
        {
            // <04>
            // Create fallback provider function
            Func<string, string[]> func = culture => new string[] { culture, "en", "" }.Distinct().ToArray();
            // Create provider
            IProvider<string, string[]> fallbackCultureProvider = Providers.Func(func).Cached();
            // Get fallback cultures
            string[] fallbackCultures = fallbackCultureProvider["fi"];
            // Print fallback cultures in evaluation order
            WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi" → "en" → ""
            // </04>
        }
        {
            // <05>
            // Get culture provider
            IProvider<string, string[]> fallbackCultureProvider = FallbackCultureProvider.NoFallback;
            // Retrieve fallback cultures
            string[] fallbackCultures = fallbackCultureProvider["fi-FI"];
            // Print fallback cultures in evaluation order
            WriteLine($"\"{String.Join("\" → \"", fallbackCultures)}\""); // "fi-FI"
            // </05>
        }
        {
            // <06>
            // Create localization
            ILocalization localization = new Localization()
                .SetFallbackCultureProvider(FallbackCultureProvider.Default)
                .AddLines(new LocalizationReaderYaml.File("fallbackcultureprovider/fallbackcultureprovider.yaml"));
            // Get localizable text
            ILocalizableText localizable = localization.LocalizableTextCached["Namespace.HelloCasual"];
            // Cultures to print with
            foreach (string requested_culture in new string[] { "en", "en-NZ", "en-AU", "en-UK", "en-US", "en-CA" })
            {
                // Localize to culture
                ILocalizedText localized = localizable.Localize(requested_culture)?.Value!;
                // Get the culture where fallback landed to
                string supplied_culture = localized.Culture;
                // Print text
                WriteLine($"{requested_culture,-5} {supplied_culture,-5}: {localized.Print(null)}");
            }
            // en    en   : Hello fella
            // en-NZ en   : Hello fella
            // en-AU en-AU: Hello mate
            // en-UK en-UK: Hello chap
            // en-US en-US: Hello dude
            // en-CA en-CA: Hello buddy
            // </06>
        }
    }
}