当我不枚举IDictionary的键和值时';我不知道值的类型
本文关键字:我不知道 类型 键和值 枚举 IDictionary | 更新日期: 2023-09-27 18:00:15
我有一个对对象的引用。我知道它符合
IDictionary<string, T>
对于某些类型T(它可能不符合普通IDictionary或IReadyOnlyDictionary)。关于T,我只知道它是从物体上下来的。如何获取它的密钥,并获取密钥的值?(我可以将值作为对象而不是T返回。我也可以从不学习T是什么。)
我想写但写不出来的东西是这样的:
public void SomeMethod(object reallyADict) { // reallyADict implements IDictionary<string, T>.
foreach (string key in reallyADict.Keys) {
object value = reallyADict[key];
// . . .
}
}
**
根据请求,下面是一个示例类。
using System;
using System.Collections.Generic;
using System.Collections;
namespace My.Collections
{
public class WrappedDictionary: IDictionary<string, int>
{
public WrappedDictionary() {
this.InnerDictionary = new Dictionary<string, int>{ {"one", 1}, {"two", 2 }};
}
private Dictionary<string, int> InnerDictionary { get; set;}
private ICollection<KeyValuePair<string, int>> InnerCollection {
get {
return this.InnerDictionary;
}
}
#region IDictionary implementation
void IDictionary<string, int>.Add(string key, int value) {
this.InnerDictionary.Add(key, value);
}
bool IDictionary<string, int>.ContainsKey(string key) {
return this.InnerDictionary.ContainsKey(key);
}
bool IDictionary<string, int>.Remove(string key) {
return this.InnerDictionary.Remove(key);
}
bool IDictionary<string, int>.TryGetValue(string key, out int value) {
return this.InnerDictionary.TryGetValue(key, out value);
}
int IDictionary<string, int>.this[string index] {
get {
return this.InnerDictionary[index];
}
set {
this.InnerDictionary[index] = value;
}
}
ICollection<string> IDictionary<string, int>.Keys {
get {
return this.InnerDictionary.Keys;
}
}
ICollection<int> IDictionary<string, int>.Values {
get {
return this.InnerDictionary.Values;
}
}
#endregion
#region ICollection implementation
void ICollection<KeyValuePair<string, int>>.Add(KeyValuePair<string, int> item) {
this.InnerCollection.Add(item);
}
void ICollection<KeyValuePair<string, int>>.Clear() {
this.InnerDictionary.Clear();
}
bool ICollection<KeyValuePair<string, int>>.Contains(KeyValuePair<string, int> item) {
return this.InnerCollection.Contains(item);
}
void ICollection<KeyValuePair<string, int>>.CopyTo(KeyValuePair<string, int>[] array, int arrayIndex) {
this.InnerCollection.CopyTo(array, arrayIndex);
}
bool ICollection<KeyValuePair<string, int>>.Remove(KeyValuePair<string, int> item) {
return this.InnerCollection.Remove(item);
}
int ICollection<KeyValuePair<string, int>>.Count {
get {
return this.InnerCollection.Count;
}
}
bool ICollection<KeyValuePair<string, int>>.IsReadOnly {
get {
return this.InnerCollection.IsReadOnly;
}
}
#endregion
#region IEnumerable implementation
IEnumerator<KeyValuePair<string, int>> IEnumerable<KeyValuePair<string, int>>.GetEnumerator() {
return this.InnerCollection.GetEnumerator();
}
#endregion
#region IEnumerable implementation
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
return (this as IEnumerable).GetEnumerator();
}
#endregion
}
}
不幸的是,您无法将reallyADict
强制转换为类似Dictionary<string,T>
的类型,因为您需要一个特定的类型。
Manfred关于使用这样的通用方法的评论
public IEnumerable<T> SomeMethod<T>(Dictionary<string, T> dict)
这也是我的做法。但你说你实际上只有object
这本字典。
所以我用反射解决了这个问题:
public IEnumerable<object> SomeMethod(object reallyADict)
{
Type genericInterface = reallyADict?.GetType().GetInterface("IDictionary`2");
PropertyInfo propKeys = genericInterface?.GetProperty("Keys");
if (propKeys?.GetMethod == null) yield break;
IEnumerable<string> keys = (IEnumerable<string>)propKeys.GetValue(reallyADict);
PropertyInfo propIndex = genericInterface.GetProperty("Item");
if (propIndex?.GetMethod == null) yield break;
foreach (string key in keys)
yield return propIndex.GetMethod.Invoke(reallyADict, new object[] { key });
}
此方法从reallyDict
(如果有)中获取Keys
属性,并将其用作IEnumerable<string>
。
然后,它对所有这些键进行迭代,并使用底层字典的indexer属性来返回值。索引器属性的名称为Item
。