c# - 如何模拟多重继承并使用反射来优化此代码？

Question

我有一个 WPF 应用程序，其中 PageItems 是模型对象。

我的主 ViewModel 有一个 PageItemViewModels 的 ObservableCollection，每个模型都根据其匹配的 PageItem 模型对象构建自身。

每个 PageItemViewModel 都继承自抽象类 BaseViewModel，以获得 INotifyPropertyChanged 功能。

每个 PageItemViewModel 还实现 IPageItemViewModel 以确保它具有所需的属性。

我最终会有大约 50 页，所以我想消除任何不必要的代码:

• 已解决(见下文):有没有办法让 PageItemViewModel 类继承 IdCode 和 Title，这样我就不必在每个类中实现它们？我无法将它们放入 BaseViewModel 中，因为其他 ViewModel 继承了它，不需要这些属性，并且我无法将它们放入 IPageItemViewModel 中，因为它只是一个接口(interface)。我知道我需要多重继承，而 C# 不支持
• 已解决(见下文):有没有办法可以摆脱 switch 语句，例如不知何故使用反射代替？

下面是一个独立控制台应用程序，它演示了我的WPF应用程序中的代码:

using System.Collections.Generic;

namespace TestInstantiate838
{
    public class Program
    {
        static void Main(string[] args)
        {
            List<PageItem> pageItems = PageItems.GetAll();
            List<ViewModelBase> pageItemViewModels = new List<ViewModelBase>();

            foreach (PageItem pageItem in pageItems)
            {
                switch (pageItem.IdCode)
                {
                    case "manageCustomers":
                        pageItemViewModels.Add(new PageItemManageCustomersViewModel(pageItem));
                        break;
                    case "manageEmployees":
                        pageItemViewModels.Add(new PageItemManageEmployeesViewModel(pageItem));
                        break;
                    default:
                        break;
                }
            }
        }
    }

    public class PageItemManageCustomersViewModel : ViewModelBase, IPageItemViewModel
    {
        public string IdCode { get; set; }
        public string Title { get; set; }

        public PageItemManageCustomersViewModel(PageItem pageItem)
        {

        }
    }

    public class PageItemManageEmployeesViewModel : ViewModelBase, IPageItemViewModel
    {
        public string IdCode { get; set; }
        public string Title { get; set; }

        public PageItemManageEmployeesViewModel(PageItem pageItem)
        {

        }
    }

    public interface IPageItemViewModel
    {
        //these are the properties which every PageItemViewModel needs
        string IdCode { get; set; }
        string Title { get; set; }
    }

    public abstract class ViewModelBase
    {
        protected void OnPropertyChanged(string propertyName)
        {
            //this is the INotifyPropertyChanged method which all ViewModels need
        }
    }

    public class PageItem
    {
        public string IdCode { get; set; }
        public string Title { get; set; }
    }

    public class PageItems
    {
        public static List<PageItem> GetAll()
        {
            List<PageItem> pageItems = new List<PageItem>();
            pageItems.Add(new PageItem { IdCode = "manageCustomers", Title = "ManageCustomers"});
            pageItems.Add(new PageItem { IdCode = "manageEmployees", Title = "ManageEmployees"});
            return pageItems;
        }
    }

}

重构:接口(interface)改为抽象类

using System;
using System.Collections.Generic;

namespace TestInstantiate838
{
    public class Program
    {
        static void Main(string[] args)
        {
            List<PageItem> pageItems = PageItems.GetAll();
            List<ViewModelPageItemBase> pageItemViewModels = new List<ViewModelPageItemBase>();

            foreach (PageItem pageItem in pageItems)
            {
                switch (pageItem.IdCode)
                {
                    case "manageCustomers":
                        pageItemViewModels.Add(new PageItemManageCustomersViewModel(pageItem));
                        break;
                    case "manageEmployees":
                        pageItemViewModels.Add(new PageItemManageEmployeesViewModel(pageItem));
                        break;
                    default:
                        break;
                }
            }

            foreach (ViewModelPageItemBase pageItemViewModel in pageItemViewModels)
            {
                System.Console.WriteLine("{0}:{1}", pageItemViewModel.IdCode, pageItemViewModel.Title);
            }
            Console.ReadLine();
        }
    }

    public class PageItemManageCustomersViewModel : ViewModelPageItemBase
    {
        public PageItemManageCustomersViewModel(PageItem pageItem)
        {
            IdCode = pageItem.IdCode;
            Title = pageItem.Title;
        }
    }

    public class PageItemManageEmployeesViewModel : ViewModelPageItemBase
    {
        public PageItemManageEmployeesViewModel(PageItem pageItem)
        {
            IdCode = pageItem.IdCode;
            Title = pageItem.Title;
        }
    }

    public abstract class ViewModelPageItemBase : ViewModelBase
    {
        //these are the properties which every PageItemViewModel needs
        public string IdCode { get; set; }
        public string Title { get; set; }
    }

    public abstract class ViewModelBase
    {
        protected void OnPropertyChanged(string propertyName)
        {
            //this is the INotifyPropertyChanged method which all ViewModels need
        }
    }

    public class PageItem
    {
        public string IdCode { get; set; }
        public string Title { get; set; }
    }

    public class PageItems
    {
        public static List<PageItem> GetAll()
        {
            List<PageItem> pageItems = new List<PageItem>();
            pageItems.Add(new PageItem { IdCode = "manageCustomers", Title = "ManageCustomers"});
            pageItems.Add(new PageItem { IdCode = "manageEmployees", Title = "ManageEmployees"});
            return pageItems;
        }
    }

}

消除 Switch 语句的答案:

谢谢贾布:

string assemblyName = System.Reflection.Assembly.GetExecutingAssembly().GetName().Name;
string viewModelName = assemblyName + ".ViewModels.PageItem" + StringHelpers.ForcePascalNotation(pageItem.IdCode) + "ViewModel";
var type = Type.GetType(viewModelName);
var viewModel = Activator.CreateInstance(type, pageItem) as ViewModelBase;
AllPageViewModels.Add(viewModel);

Answer 1

您能否创建一个继承自 BaseViewModel 的类来实现这两个属性 - 然后您需要此属性的 PageItemViewModel 类可以继承该类。