如何创建在C＃中的动态特性？ [英] How do I create dynamic properties in C#?

问题描述

我要寻找一种方式来创建一个类与一组静态属性。在运行时，我希望能够到其他动态属性到这个对象从数据库中添加。我也想补充的排序和过滤功能对这些对象。

I am looking for a way to create a class with a set of static properties. At run time, I want to be able to add other dynamic properties to this object from the database. I'd also like to add sorting and filtering capabilities to these objects.

我怎么做这在C＃？

推荐答案

您可以使用一本字典，说

You might use a dictionary, say

Dictionary<string,object> properties;

我认为在类似的东西做，它的完成这样的大多数情况下。

在任何情况下，你不会从创建一套与真正的财产获得任何东西，获得访问，因为它只会在运行时创建，你就不会在code。使用它来...

I think in most cases where something similar is done, it's done like this.
In any case, you would not gain anything from creating a "real" property with set and get accessors, since it would be created only at run-time and you would not be using it in your code...

下面是一个例子，示出了一个可能的实现过滤和排序（没有错误检查）：

Here is an example, showing a possible implementation of filtering and sorting (no error checking):

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication1 {

    class ObjectWithProperties {
        Dictionary<string, object> properties = new Dictionary<string,object>();

        public object this[string name] {
            get { 
                if (properties.ContainsKey(name)){
                    return properties[name];
                }
                return null;
            }
            set {
                properties[name] = value;
            }
        }

    }

    class Comparer<T> : IComparer<ObjectWithProperties> where T : IComparable {

        string m_attributeName;

        public Comparer(string attributeName){
            m_attributeName = attributeName;
        }

        public int Compare(ObjectWithProperties x, ObjectWithProperties y) {
            return ((T)x[m_attributeName]).CompareTo((T)y[m_attributeName]);
        }

    }

    class Program {

        static void Main(string[] args) {

            // create some objects and fill a list
            var obj1 = new ObjectWithProperties();
            obj1["test"] = 100;
            var obj2 = new ObjectWithProperties();
            obj2["test"] = 200;
            var obj3 = new ObjectWithProperties();
            obj3["test"] = 150;
            var objects = new List<ObjectWithProperties>(new ObjectWithProperties[]{ obj1, obj2, obj3 });

            // filtering:
            Console.WriteLine("Filtering:");
            var filtered = from obj in objects
                         where (int)obj["test"] >= 150
                         select obj;
            foreach (var obj in filtered){
                Console.WriteLine(obj["test"]);
            }

            // sorting:
            Console.WriteLine("Sorting:");
            Comparer<int> c = new Comparer<int>("test");
            objects.Sort(c);
            foreach (var obj in objects) {
                Console.WriteLine(obj["test"]);
            }
        }

    }
}

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