private Book(Author author, ISBN13 isbn13, Int1000 pages, Maybe <RatingEnum> rating)
{
_author = author;
_isbn13 = isbn13;
_pages = pages;
_rating = rating;
}
public static ValidationResult <Book> Create(string author, string isbn13, int pages, string rating)
{
ValidationResult <Author> authorResult = Author.Create(author);
ValidationResult <ISBN13> isbn13Result = ISBN13.Create(isbn13);
ValidationResult <Int1000> pagesResult = Int1000.Create(pages);
ValidationResult <Maybe <RatingEnum> > ratingResult = Spec.Optional(x => !String.IsNullOrWhiteSpace(x), Rating.Create, rating);
return(ValidationResult.Combine(authorResult, isbn13Result, pagesResult, ratingResult, (auth, isbn, ps, r) => new Book(auth, isbn, ps, r)));
}
