using System; namespace VersOne.Epub.Schema { /// /// Represents a subject of the EPUB book. /// /// See , /// , /// and for more information. /// /// public class EpubMetadataSubject { /// /// Initializes a new instance of the class. /// /// The text content of this subject. /// The unique ID of this subject or null if the subject doesn't have an ID. /// The text direction of this subject or null if the subject doesn't specify a text direction. /// The language of this subject or null if the subject doesn't specify the language. /// The parameter is null. public EpubMetadataSubject(string subject, string? id = null, EpubTextDirection? textDirection = null, string? language = null) { Subject = subject ?? throw new ArgumentNullException(nameof(subject)); Id = id; TextDirection = textDirection; Language = language; } /// /// Gets the text content of this subject. /// /// See , /// , /// and for more information. /// /// public string Subject { get; } /// /// Gets the unique ID of this subject or null if the subject doesn't have an ID. /// See for more information. /// public string? Id { get; } /// /// Gets the text direction of this subject or null if the subject doesn't specify a text direction. /// See for more information. /// public EpubTextDirection? TextDirection { get; } /// /// Gets the language of this subject or null if the subject doesn't specify the language. /// See for more information. /// public string? Language { get; } } }