C# 将泛型委托(delegate)传递给构造函数

Question

我是 C# 的新手，我试图找到一种将通用委托(delegate)传递给构造函数的方法。

调用显示端点时，如果有分页，端点应返回一个 Page 实例。创建 Page 实例时，委托(delegate)方法应作为构造函数参数之一传递。 ShowsEndpoints 将托管许多端点，其中许多端点使用分页。我只想使用一个类来处理所有端点。

public partial class ShowsEndpoints : Endpoint
{
    public Func<Task<IEnumerable<object>>> FetchPopularShowsAsyncDelegate;
    public Func<Task<IEnumerable<object>>> FetchTrendingShowsAsyncDelegate;
    public Func<Task<IEnumerable<object>>> FetchMostWatchedShowsAsyncDelegate;

    public async Task<IEnumerable<object>> FetchPopularShowsAsync(int page = 1, int limit = 20)
    {
        return await SendAsync(new PopularShowsRequest(page, limit));
    }

    public async Task<IEnumerable<object>> FetchTrendingShowsAsync(int page = 1, int limit = 20)
    {
        return await SendAsync(new TrendingShowsRequest(page, limit));
    }

    public async Task<IEnumerable<object>> FetchMostWatchedShowsAsync(int page = 1, int limit = 20)
    {
        return await SendAsync(new MostWatchedShowsRequest(page, limit));
    }
}

如果有下一页，将调用委托(delegate)来获取下一页的页面类。

public class Page<TItem, TDelegate>
{
    private TDelegate _delegateCommand;

    public int CurrentPage { get; }
    public int TotalPages { get; }
    public int PageItemsCount { get; }
    public int TotalItemsCount { get; }
    public IEnumerable<TItem> Items { get; }

    public Page(int page, int totalPages, int itemsCount, int totalItemsCount, IEnumerable<TItem> items, TDelegate delegateCommand)
    {
        CurrentPage = page;
        TotalPages = totalPages;
        PageItemsCount = itemsCount;
        TotalItemsCount = totalItemsCount;
        Items = items;
        _delegateCommand = delegateCommand;
    }

    public bool HasNext()
    {
        return CurrentPage <= TotalPages;
    }

    public bool HasPrevious()
    {
        return CurrentPage >= 1;
    }

    public Page<TItem, TDelegate> Next()
    {
        // call _delegateCommand to fetch the next page items
    }

    public Page<TItem, TDelegate> Previous()
    {
        // call _delegateCommand to fetch the previous page items
    }
}

这可能吗？

谢谢。

编辑

为了更好地理解我的问题，我更新了我的类(class)代码。我有 3 个端点与他们的委托(delegate)相关联，我希望 Page 类使用这 3 个委托(delegate)中的任何一个具有相同的代码以避免重复。所以 _delegateCommand 可以是 FetchPopularShowsAsyncDelegate、FetchTrendingShowsAsyncDelegate 或 FetchMostWatchedShowsAsyncDelegate。

Answer 1

我不确定我是否达到了 _delegateCommand 的目的对 - 我猜应该是函数返回 IEnumerable<TItem> .如果是这样，那么你就可以像这样声明它，然后你就不必再引入另一个泛型参数了:

public class Page<TItem>
{
    private Func<IEnumerable<TItem>>_delegateCommand;

    public int CurrentPage { get; }
    public int TotalPages { get; }
    public int PageItemsCount { get; }
    public int TotalItemsCount { get; }
    public IEnumerable<TItem> Items { get; }

    public Page(int page, int totalPages, int itemsCount,
                int totalItemsCount, IEnumerable<TItem> items,
                Func<IEnumerable<TItem>> delegateCommand)
    {
        CurrentPage = page;
        TotalPages = totalPages;
        PageItemsCount = itemsCount;
        TotalItemsCount = totalItemsCount;
        Items = items;
        _delegateCommand = delegateCommand;
    }

    public bool HasNext()
    {
        return CurrentPage <= TotalPages;
    }

    public bool HasPrevious()
    {
        return CurrentPage >= 1;
    }
}