我有哪里的要求:1。 我需要存储在列表中的任何类型的对象 2.避免铸造呼吁尽可能C# - 任何类似于boost :: any的东西?
为此我试图来的东西。无论我尝试过什么,我都无法摆脱拳击\拆箱。我想知道你们中是否有人遇到过能够实现这一目标的事情。
我创建的类几乎没有用处,除非您处理的是小集合,因为在内存和性能方面它需要1.5倍ArrayList。我试图找到改善其中至少一个的方法(最好是性能)。
任何反馈意见。
public class Castable
{
Object _o;
public override bool Equals(object obj) { return base.Equals(obj); }
public override int GetHashCode() { return base.GetHashCode(); }
public bool Equals<T>(T obj)
{
T v1 = (T)this._o;
//T v2 = obj;
//var v2 = obj; // Convert.ChangeType(obj, obj.GetType());
// This doesn't work.. (Cannot convert T to Castable
//var v2 = Convert.ChangeType(this.GetType() == obj.GetType() ?
//((Castable)obj)._o.GetType(), obj.GetType());
//if (((T)this._o) != obj) //<== why this doesn't work?
//if (v1 == obj) //<== "Operator '==' cannot be applied to operands of type 'T' and 'T'"
if(v1.Equals(obj))
{
return true;
}
return false;
}
public bool Equals(Castable obj)
{
var v = Convert.ChangeType(obj._o, obj._o.GetType());
return Equals(v);
}
public static bool operator ==(Castable a, Castable b)
{
return a.Equals(b);
}
public static bool operator !=(Castable a, Castable b)
{
return !a.Equals(b);
}
#region HOW CAN WE USE GENRIC TYPE FOR == and != OPERATOR?
public static bool operator ==(Castable a, object b)
{
return a.Equals(b);
}
public static bool operator !=(Castable a, object b)
{
return !a.Equals(b);
}
#endregion
public void Set<T>(T t) { _o = t; }
public T Get<T>() { return (T)_o; }
public static long TestLookup(IList list, int elements, int lookups)
{
object value;
Stopwatch watch = new Stopwatch();
watch.Start();
for (long index = 0; index < lookups; ++index)
{
value = list[random.Next(0, elements - 1)];
}
watch.Stop();
return watch.ElapsedMilliseconds;
}
public static long TestCompare(IList list, int elements, int lookups)
{
//object value;
bool match;
Stopwatch watch = new Stopwatch();
watch.Start();
for (long index = 0; index < lookups; ++index)
{
match = random.Next() == (int)list[random.Next(0, elements - 1)];
}
watch.Stop();
return watch.ElapsedMilliseconds;
}
public static long TestCompareCastable(IList<Castable> list, int elements, int lookups)
{
//object value;
bool match;
Stopwatch watch = new Stopwatch();
watch.Start();
for (long index = 0; index < lookups; ++index)
{
match = list[random.Next(0, elements - 1)] == random.Next(); //most of the times 1.4 times
//match = list[random.Next(0, elements - 1)].Equals(random.Next()); // may be 1.3 times ArrayList
}
watch.Stop();
return watch.ElapsedMilliseconds;
}
public static void Test(int elements, int lookups, int times)
{
List<int> intList = new List<int>();
List<Castable> castableList = new List<Castable>();
ArrayList intArrayList = new ArrayList();
if (Stopwatch.IsHighResolution)
Console.WriteLine("We have a high resolution timer available");
long frequency = Stopwatch.Frequency;
Console.WriteLine(" Timer frequency in ticks per second = {0}", frequency);
for (int index = 0; index < elements; ++index)
{
intList.Add(random.Next());
intArrayList.Add(random.Next());
Castable c = new Castable();
c.Set(random.Next());
castableList.Add(c);
}
long ms = 0;
string result = "";
string ratios = "";
for (int time = 0; time < times; ++time)
{
ms = TestLookup(intList, elements, lookups);
result += "intList Lookup Time " + ms.ToString() + " MS\n";
ms = TestLookup(castableList, elements, lookups);
result += "intArrayList Lookup Time " + ms.ToString() + " MS\n";
ms = TestLookup(intArrayList, elements, lookups);
result += "castableList Lookup Time " + ms.ToString() + " MS\n";
ms = TestCompare(intList, elements, lookups);
result += "intList Compare Time " + ms.ToString() + " MS\n";
long msarraylist = ms = TestCompare(intArrayList, elements, lookups);
result += "intArrayList Compare Time " + ms.ToString() + " MS\n";
ms = TestCompareCastable(castableList, elements, lookups);
result += "castableList Compare Time " + ms.ToString() + " MS\n";
ratios += String.Format("round: {0}, ratio: {1}\n", time, (float)ms/msarraylist);
}
//MessageBox.Show(result);
MessageBox.Show(ratios);
int i = 10;
Castable o1 = new Castable();
o1.Set(i);
int j = 10;
Castable o2 = new Castable();
o2.Set(j);
if (!o1.Equals(10))
{
Console.WriteLine("unequal");
}
if (!o1.Equals(o2))
{
Console.WriteLine("unequal");
}
if (o1 != j)
{
Console.WriteLine("unequal");
}
int x = o1.Get<int>();
}
}
编辑
总之我想实现:
@ winSharp93:是的,在短: 列表GenericGenericCollection =新名单();
GenericGenericCollection.Add(新字符串( “十四行诗”);
GenericGenericCollection.Add(42);
GenericGenericCollection.Add(新MyOwnCustomType);
再次编辑
有两种我发现的方法: 1.在.NET 4中引入了一个新的'dynamic'关键字,如果用dynamic _o;
代替行Object _o;
,您可以照原样使用代码。问题是虽然动态应该是动态的类型,性能就像拳击..
性能可以通过添加隐式的(我喜欢)或显式转换操作符,而不是依赖于通用的==操作符来提高。
根据http://igoro.com/archive/fun-with-c-generics-down-casting-to-a-generic-type/我添加了以下类。这需要关心拳击和性能 - 下面的类的性能比int或Castable的ArrayList好一点。当然,当
List<int>
比较时,它还有很长的路要走。 从我的角度来看,唯一的问题是,一旦将对象分配给普通Any对象以获取嵌入在AnyInternal<T>
内部的具体类型。我也无法找到方法T Get()
。即使关键字的动态在运行时出现故障,在statment:
Any.AnyInternal<dynamic> any = (Any.AnyInternal<dynamic>)anyInstanceContainingAnyInternalForInt;
//too bad I can't seal Any after AnyInternal<T> has derived from it.
public abstract class Any
{
public static implicit operator int(Any any)
{
return Any.ToType<int>(any).Data;
}
public static AnyInternal<T> ToType<T>(Any any)
{
return ((AnyInternal<T>)any);
}
public class AnyInternal<T> : Any
{
private T _data;
public T Data { get { return _data; } }
public AnyInternal(T data)
{
_data = data;
}
}
}
你为什么不把你的类型声明为Castable,并将_o声明为T类型? –
2012-02-23 11:56:46
因为它将Castable绑定到T,我想要一个列表,其中Castable没有绑定到类型。 – 2012-02-23 12:03:06
我会退后一步,看看手头的问题。如果集合中的拳击对你来说是一个问题,我会考虑实现我自己的集合,它内部拥有多个内部集合。一个用于已知的值类型,另一个用于对象。创建Add方法的重载将允许您将正确的项目放在正确的内部集合中 – Polity 2012-02-23 12:09:09