c# - 在 C# 中将泛型委托(delegate)作为方法参数传递

Question

我有这个委托(delegate)声明:

public delegate IEnumerable<T> SearchInputTextStrategy<T, U>(string param);

假设我确实在这里创建了新的 SearchInputTextStrategy 委托(delegate)并将其命名为 MyDelegate。

这是我的方法声明:

public void BindElements<T, TDisplayProperty,TSortProperty>
(
       IEnumerable<T> dataObjects,
       Func<T, TDisplayProperty> selectorDisplayMember,
       Func<T, TSortProperty> selectorSortMember,
       string delimiter,
       // 1.) how to declare the delegate here as parameter ??
)
{
    // pass here the delegate to a private field to save it
    // 2.) how can I do that?

}

我该怎么做 1.) 和 2.)？ :-)

更新 2:

好的，这就是我到目前为止所做的:

public class SearchProvider<T>
    {
        public delegate IEnumerable<T> SearchInputTextStrategy<T>(string param);    

        public SearchInputTextStrategy<T> SearchStrategy { get; set; }

        public T TypedValue
        {
            get
            {
                return (T)Convert.ChangeType(SearchStrategy, typeof(T));
            }
        }
    }

用户控件:

 public delegate IEnumerable<T> SearchInputTextStrategy<T>(string param);

 public void BindElements<T, TDisplayProperty,TSortProperty>
        (
            IEnumerable<T> dataObjects,
            Func<T, TDisplayProperty> selectorDisplayMember,
            Func<T, TSortProperty> selectorSortMember,
            string delimiter,
            SearchInputTextStrategy<T> searchStrategy
        )
        { 
               /// assign the searchStrategy to the SearchProvider class 
            var sp = new SearchProvider<T>();
                sp.SearchStrategy = searchStrategy  // DOES NOT WORK !!!     
        }

另请阅读我在准则中的评论。我想要实现的是将委托(delegate)传递给 searchProvider 以将其保存在某个地方......我在这里编写的代码我理解高达 50％所以请耐心等待泛型对我来说是新的虽然我使用泛型列表很长时间;

更新 2:

公共(public)部分类 MainWindow : Window { 公共(public)委托(delegate) IEnumerable SearchInputTextStrategy(string param);

    private SearchInputTextStrategy<ICustomer> _strategy;

    public MainWindow()
    {
        InitializeComponent();            

        IEnumerable<ICustomer> customers = DataService.GetCustomers();                  

        _strategy = new SearchInputTextStrategy<ICustomer>(SearchCustomers);           


        ElementUserControl.BindElements(customers, c => c.FirstName, c => c.SortId, ";", _strategy);

namespace ElementTextBoxV2
{      

        public partial class MainWindow : Window
        {
            public delegate IEnumerable<ICustomer> SearchInputTextStrategy<ICustomer>(string param);

            private SearchInputTextStrategy<ICustomer> _strategy;

            public MainWindow()
            {
                InitializeComponent();            

                IEnumerable<ICustomer> customers = DataService.GetCustomers();                  

                _strategy = new SearchInputTextStrategy<ICustomer>(SearchCustomers);           


                ElementUserControl.BindElements(customers, c => c.FirstName, c => c.SortId, ";", _strategy);

                IEnumerable<ICustomer> selectedElements =  ElementUserControl.SelectedElements<ICustomer>();
            }

            // Just a Test-Methode to assure the delegate works
            public IEnumerable<ICustomer> SearchCustomers(string param)
            {
                IEnumerable<ICustomer> foundCustomers = new List<ICustomer>();
                return foundCustomers;
            }         
        }
    }

场景是，用户将 TextBoxUserControl 放在 MainWindow 中，他必须传递一个指向 searchMethod 的委托(delegate)。我已经使用 SearchCustomers_Method 实现了这一点。问题是 C# 无法解决:

    Error   1   The best overloaded method match for 'ElementTextBoxV2.ElementsView.BindElements<ElementTextBoxV2.ICustomer,string,int>(System.Collections.Generic.IEnumerable<ElementTextBoxV2.ICustomer>, System.Func<ElementTextBoxV2.ICustomer,string>, System.Func<ElementTextBoxV2.ICustomer,int>, string, ElementTextBoxV2.Provider.SearchInputTextStrategy<ElementTextBoxV2.ICustomer>)' has some invalid arguments

Error   2   Argument 5: cannot convert from 'ElementTextBoxV2.MainWindow.SearchInputTextStrategy<ElementTextBoxV2.ICustomer>' to 'ElementTextBoxV2.Provider.SearchInputTextStrategy<ElementTextBoxV2.ICustomer>'    

你看到问题了吗？在任何情况下，用户都必须传递与 BindElements 方法具有相同定义的委托(delegate)!

Answer 1

奇怪的是，您的 SearchInputTextStrategy 有两个类型参数，但实际上只使用了一个……但是您只需要在参数类型中指定类型参数。例如:

public void BindElements<T, TDisplayProperty,TSortProperty>
(
    IEnumerable<T> dataObjects,
    Func<T, TDisplayProperty> selectorDisplayMember,
    Func<T, TSortProperty> selectorSortMember,
    string delimiter,
    SearchInputTextStrategy<T, TDisplayProperty> searchStrategy
)

我只是猜测参数的类型应该是什么——你还没有真正说出你希望参数委托(delegate)什么。

您将无法轻松地在类中拥有正确类型的字段，因为类本身不知道涉及的类型参数。您可能真的应该让您的类成为通用类，或者制作另一个 能够适当处理委托(delegate)的类。没有更多信息，很难知道是哪一个。