我知道这个问题已经被问过，但我还没有看到很短的，明确的答案，所以我希望他们不会消除这个问题，现在我会得到一个明确的答案：

I know this question has been asked before, but I have yet to see a short, clear answer, so I'm hoping they won't remove this question and I will now get a clear answer:

我目前工作在C＃5.0; .NET 4.5; VS 2012年我主要是一个Delphi的人，虽然我已经用C＃做了很多。

I am currently working in C# 5.0; .NET 4.5; VS 2012. I am mostly a Delphi guy although I've done lots with C#.

在德尔福我已经写了数百名使用以下排序设计（大大简化HERE）类工厂：

In Delphi I have written hundreds of class factories that use the following sort of design (MUCH SIMPLIFIED HERE):

unit uFactory;

interface


type

    TClassofMyClass = class of TMyClass;
    TFactoryDict = TDictionary<TMyEnum, TClassofMyClass>;

var fDict:TFactoryDict;

implementation  

procedure initDict;
begin

    fDict:=TFactoryDict.create;
    fDict.add(myEnum1, TMyClass1);
    fDict.add(myEnum2, TMyClass2);
    fDict.add(myEnum3, TMyClass3);

end;


function Factory(const aEnum: TMyEnum): TMyClass;

var

    ClassofMyClass: TClassofMyClass;

begin

    if fDict.TryGetValue(aEnum, ClassofMyClass) then

    result := ClassofMyClass.Create(aParam);

end;

end.

现在：做我怎么做这样的事在C＃？似乎还有否在C＃中类的类型。我失去了一些东西？我怎样才能实现这种类型的类工厂的简单和优雅的C＃？这样的设计可以在Python实现以及 - ？！为什么C＃是雪上加霜

Now: HOW do I do something like this in C#?! Seems there is NO 'class of ' type in C#. Am I missing something? How can I implement this type of class factory simply and elegantly in C#? This design can be implemented in Python as well - why should C# be worse?!

推荐答案

您可以使用Type：

Dictionary<ClassEnum, Type> TypeDictionary = new Dictionary<ClassEnum, Type>();

public void InitDictionary()
{
    TypeDictionary.Add(ClassEnum.FirstClass, typeof(FirstClass));
    //etc...
}

public object Factory(ClassEnum type)
{
    if (!TypeDictionary.ContainsKey(type))
        return null;

    var constructor = TypeDictionary[type].GetConstructor(....);
    return constructor.Invoke(....);
}

不过，我认为你应该使用泛型方法：

But I think you should use a generic method:

public T Factory<T>(): where T is MyBaseClass
{
    var type = typeof(T);
    var constructor = type.GetConstructor(....);
    return constructor.Invoke(....) as T;
}

下面是各种参数化建设：

Here is a variety for parameterized construction:

public T Factory<T>(params object[] args): where T is MyBaseClass
{
    var argList = new List<object>(args);
    var type = typeof(T);
    var argtypes = argList.Select(o => o.GetType()).ToArray();
    var constructor = type.GetConstructor(argtypes);
    return constructor.Invoke(args) as T;
}

当然，正如第一个例子，这将抛出一个NullPointerException异常，如果它不能找到匹配的构造......

And of course; As with the first example, this will throw a nullpointerexception if it can't find a matching constructor...