Общие ограничения интерфейса

Question

Я пытаюсь уменьшить следующий кусок кода:

public interface IQuestion<TSite, TStyling, TRelation> : IShallowPost
    where TSite : INetworkSite<TStyling, TRelation>
    where TStyling : INetworkSiteStyling
    where TRelation : INetworkSiteRelation
{

Примерно так:

public interface IQuestion<TSite> : IShallowPost
    where TSite : INetworkSite<TStyling, TRelation>
    where TStyling : INetworkSiteStyling
    where TRelation : INetworkSiteRelation
{

Как я могу заставить это работать?

Так как что-то вроде этого:

internal sealed class Question : IQuestion<NetworkSite, NetworkSiteStyling, NetworkSiteRelation>

Имеет для меня очень мало смысла по сравнению с

internal sealed class Question : IQuestion<NetworkSite>

Обновление @ Джаред

Конечно, это было бы так.

/// <summary>
/// Represents a question on one of the Stack Exchange sites.
/// <para>https://api.stackexchange.com/docs/types/question</para>
/// </summary>
/// <typeparam name="TSite">The concrete type of <see cref="INetworkSite{TStyling,TRelation}"/>.</typeparam>
/// /// <typeparam name="TStyling">The concrete type of <see cref="INetworkSiteStyling"/>.</typeparam>
/// <typeparam name="TRelation">The concrete type of <see cref="INetworkSiteRelation"/>.</typeparam>
/// <typeparam name="TMigrationInfo">The concrete type of <see cref="IMigrationInfo{TSite,TStyling,TRelation}"/>.</typeparam>
/// <typeparam name="TShallowUser">The concrete type of <see cref="IShallowUser"/>.</typeparam>
/// <typeparam name="TComment">The concrete type of <see cref="IComment{TShallowUser}"/>.</typeparam>
/// <typeparam name="TAnswer">The concrete type of <see cref="IAnswer{TShallowUser,TComment}"/>.</typeparam>
public interface IQuestion<TShallowUser, TComment, TMigrationInfo, TSite, TStyling, TRelation, TAnswer> : IShallowPost<TShallowUser, TComment>
    where TShallowUser : IShallowUser
    where TComment : IComment<TShallowUser>
    where TSite : INetworkSite<TStyling, TRelation>
    where TStyling : INetworkSiteStyling
    where TRelation : INetworkSiteRelation
    where TMigrationInfo : IMigrationInfo<TSite, TStyling, TRelation>
    where TAnswer : IAnswer<TShallowUser, TComment>
{
    /// <summary>
    /// The id of this question.
    /// </summary>
    [JsonProperty("question_id")]
    long? QuestionId { get; set; }
    /// <summary>
    /// The date this question was locked.
    /// </summary>
    [JsonConverter(typeof(UnixDateTimeConverter))]
    [JsonProperty("locked_date")]
    DateTime? LockedDate { get; set; }
    /// <summary>
    /// The date this question was marked as community wiki.
    /// </summary>
    [JsonConverter(typeof(UnixDateTimeConverter))]
    [JsonProperty("community_owned_date")]
    DateTime? CommunityOwnedDate { get; set; }
    /// <summary>
    /// The amount of answers posted in response to this question.
    /// </summary>
    [JsonProperty("answer_count")]
    long? AnswerCount { get; set; }
    /// <summary>
    /// The id of the accepted answer, if any.
    /// </summary>
    [JsonProperty("accepted_answer_id")]
    long? AcceptedAnswerId { get; set; }
    /// <summary>
    /// Migration info telling where this question was migrated to.
    /// </summary>
    [JsonProperty("migrated_to")]
    TMigrationInfo MigratedTo { get; set; }
    /// <summary>
    /// Migration info telling where this question was migrated from.
    /// </summary>
    [JsonProperty("migrated_from")]
    TMigrationInfo MigratedFrom { get; set; }
    /// <summary>
    /// Date when the active bounty on this question ends.
    /// </summary>
    [JsonConverter(typeof(UnixDateTimeConverter))]
    [JsonProperty("bounty_closes_date")]
    DateTime? BountyClosesDate { get; set; }
    /// <summary>
    /// The amount of reputation spent on the bounty.
    /// </summary>
    [JsonProperty("bounty_amount ")]
    long? BountyAmount { get; set; }
    /// <summary>
    /// The date this question was closed.
    /// </summary>
    [JsonConverter(typeof(UnixDateTimeConverter))]
    [JsonProperty("closed_date")]
    DateTime? ClosedDate { get; set; }
    /// <summary>
    /// The date this question was marked as protected.
    /// </summary>
    [JsonConverter(typeof(UnixDateTimeConverter))]
    [JsonProperty("protected_date")]
    DateTime? ProtectedDate { get; set; }
    /// <summary>
    /// The title of this question.
    /// </summary>
    [JsonProperty("title")]
    string Title { get; set; }
    /// <summary>
    /// A list of tags applied on this question.
    /// </summary>
    [JsonProperty("tags")]
    IList<string> Tags { get; set; }
    /// <summary>
    /// The reason this post was closed.
    /// </summary>
    [JsonProperty("closed_reason")]
    string ClosedReason { get; set; }
    /// <summary>
    /// The amount of users who favorited this question.
    /// </summary>
    [JsonProperty("favorite_count")]
    long? FavoriteCount { get; set; }
    /// <summary>
    /// The amount of views this question had.
    /// </summary>
    [JsonProperty("view_count")]
    long? ViewCount { get; set; }
    /// <summary>
    /// A list of answers posted on this question.
    /// </summary>
    [JsonProperty("answers")]
    IList<TAnswer> Answers { get; set; }
    /// <summary>
    /// A link to the question.
    /// </summary>
    [JsonProperty("link")]
    string Link { get; set; }
    /// <summary>
    /// A boolean indicating whether this question is answered or considered unanswered.
    /// </summary>
    [JsonProperty("is_answered")]
    bool? IsAnswered { get; set; }
}

Мне нужны конкретные типы вместо интерфейсов из-за десериализации Json, но я действительно ненавижу обходить эти огромные списки универсальных типов. Это ужасно.

Answer 1

Вы можете сделать это ограничение короче, если вы используете C # 4 или выше и объявите оба параметра типа INetworkSite как ковариантные, что сделает ваши интерфейсы похожими на:

public interface IQuestion<TSite> : IShallowPost
    where TSite : INetworkSite<INetworkSiteStyling, INetworkSiteRelation>
{
    // interface members
}

public interface INetworkSite<out TStyling, out TRelation>
    // these constraints are not actually needed for the example to work,
    // but they seemed logical, so I left them in
    where TStyling : INetworkSiteStyling
    where TRelation : INetworkSiteRelation
{
    // interface members
}

однако, если INetworkSiteтребует какого-либо ввода данных указанных типов (параметров метода, параметров ref, настраиваемых свойств), это не сработает, поэтому вы вынуждены оставить ограничение как есть.

Конечно, возможноопределить только один параметр типа как ковариантный, что позволяет оставить только один параметр вне ограничения.