[LINQ 擴充 - 然後呢] "然後呢"擴充方法 #C# #dotnet

ThenExtension.cs

public static class ThenExtension
{
    /// <summary>
    /// "然後呢"擴充方法
    /// </summary>
    /// <typeparam name="T">原本的物件型別</typeparam>
    /// <param name="instance">原本的物件</param>
    /// <param name="fn">然後你要執行什麼，並回傳變更後的物件</param>
    /// <returns>原本的物件，可能會變更原本物件的屬性值</returns>
    public static T Then<T>(this T instance, Func<T, T> fn) => fn(instance);

    /// <summary>
    /// "然後呢"擴充方法
    /// </summary>
    /// <typeparam name="TSource">原本的物件型別</typeparam>
    /// <typeparam name="TResult">不同型別的物件</typeparam>
    /// <param name="instance">原本的物件</param>
    /// <param name="fn">然後你要執行什麼，並回傳變更後的物件</param>
    /// <returns>不同型別的物件，和原本的物件型別不同</returns>
    public static TResult Then<TSource, TResult>(this TSource instance, Func<TSource, TResult> fn) => fn(instance);

    /// <summary>
    /// "然後呢"擴充方法
    /// </summary>
    /// <typeparam name="T">原本的物件型別</typeparam>
    /// <param name="instance">原本的物件</param>
    /// <param name="fn">然後你要執行什麼</param>
    /// <returns>原本的物件，不會變更任何屬性值</returns>
    public static T Then<T>(this T instance, Action<T> fn) { fn(instance); return instance; }
}