generate extension-methods for classic ResXFileCodeGenerator types

[earloc]

As a developer, I want the source-generator to generate typed extension-methods for already existing types that are generated by the classic ResXFileGenerator``, in order to leverage typed access to interpolated ressources.

[earloc]

Closing, as the generated types only contain static-properties, which cannot be extended in a way that actually make sense. Also, using these types should be avoided, as they tend to be problematic in multi-threaded(-multi-cultured) apps, due to their nature of heavily relying on those statics.

People should find a way to introduce the usage of IStringLocalizer in their apps.

Maybe a FAQ could help people in guiding theit way to adopt TypealizR?

[earloc]

Recently revisited possibilities to support this based on this discussions over at #78.

SamplesWithCode.resx

<root>
  <data name="Greeting" xml:space="preserve">
    <value>Cheers!</value>
  </data>
  <data name="Hello {world:s}" xml:space="preserve">
    <value>Hello '{0}'</value>
  </data>
</root>

SamplesWithCode.Designer.cs

    internal class SamplesWithCode {
        //other stuff ommited for simplicity

        /// <summary>
        ///   Looks up a localized string similar to Cheers!.
        /// </summary>
        internal static string Greeting {
            get {
                return ResourceManager.GetString("Greeting", resourceCulture);
            }
        }
        
        /// <summary>
        ///   Looks up a localized string similar to Hello &apos;{0}&apos;.
        /// </summary>
        internal static string Hello__world_s_ {
            get {
                return ResourceManager.GetString("Hello {world:s}", resourceCulture);
            }
        }
    }

A feasable approach could be to generate the following code for a *ResXFileCodeGenerator-enabled file:

SamplesWithCodeExtensions.cs

internal static class SamplesWithCodeExtensions
{
    static LocalizedString GetLocalizable(string key, params object[] args)
    {
        var value = key;
        var raw = SamplesWithCode.ResourceManager.GetString(key, SamplesWithCode.Culture);
        if (raw is not null)
        {
            value = raw;
        }

        var formattedValue = string.Format(value, args);

        return new LocalizedString(key, formattedValue, raw is null);
    }

    public static LocalizedString Hello__world(this SamplesWithCode _, string world)
        => GetLocalizable("Hello {world:s}", world);

    public static LocalizedString Greeting(this SamplesWithCode _)
        => GetLocalizable("Greeting");
}

Which then could be used as:

var x = new SamplesWithCode(); //generated class by *ResXFileCodeGenerator

Console.WriteLine(x.Greeting());  // generated by TypealizR
Console.WriteLine(x.Hello__world("earth"));  // generated by TypealizR

The key here is to use the type generated by *ResXFileCodeGenerator just as a marker-type for the extension class.
Sadly, these types are not generated as partial, which would open a slight different approach. But extension-methods seem OK to achieve the desired result.

[earloc]

Maybe the generated methods need an additional IFormatProvider-parameter or any other mechnism to get rid of the dependency on the internal static global::System.Globalization.CultureInfo Culture-property from those *.Designer.cs files.