gistfile1.cs

// Should allow for this syntax:
// RuleFor(x => x.Surname).NotNull().WithLocalizedMessage(() => MyResources.SomeResource, x => "foo", x => "bar");
// ...where MyResources.SomeResource has format placeholders

public static IRuleBuilderOptions<T, TProperty> WithLocalizedMessage<T, TProperty>(this IRuleBuilderOptions<T, TProperty> rule, Expression<Func<string>> resourceSelector, params Func<T, object>[] funcs) {
	return rule.Configure(config => {
		config.CurrentValidator.ErrorMessageSource = LocalizedStringSource.CreateFromExpression(resourceSelector, new StaticResourceAccessorBuilder());

		funcs
			.Select(func => new Func<object, object>(x => func((T)x)))
			.ForEach(config.CurrentValidator.CustomMessageFormatArguments.Add);
	});
}