具有泛型基类的派生类的集合 [英] Collection of derived classes that have generic base class

问题描述

假设我有几个派生类，它们的基类是泛型类.每个派生类继承具有特定类型覆盖的基类(但所有类型也派生自单个基类型).

Say I have several derived classes whose base class is a generic class. Each derived class inherit the base class with a specific type override(but all types are also derived from a single base type).

例如:

我有一个基行类

class RowBase
{
    //some properties and abstract methods
}

我有两个从行基类派生的特定行类

And I have two specific row classes that are derived from the row base class

class SpecificRow1 : RowBase
{
    //some extra properties and overrides
}

class SpecificRow2 : RowBase
{
    //some extra properties and overrides
}

然后我有第二个基类，它是一个泛型类，它包含一组来自 RowBase 的派生类

Then I have a second base class that is a generic class which contains a collection of derived classes from RowBase

class SomeBase<T> where T : RowBase
{
    ICollection<T> Collection { get; set; }
    //some other properties and abstract methods
}

然后我有两个类派生自 SomeBase 但使用不同的特定行类

Then I have two classes that derive from SomeBase but are using different specific row class

class SomeClass1 : SomeBase<SpecificRow1>
{
     //some properties and overrides
}

class SomeClass2 : SomeBase<SpecificRow2>
{
     //some properties and overrides
}

现在，在我的主要范围或更大的范围内，我想创建一个包含 SomeClass1 和 SomeClass2 对象的列表/集合.喜欢

Now that in my main or a bigger scope, I want to create a list/collection that consist both SomeClass1 and SomeClass2 objects. Like

ICollection<???> CombinedCollection = new ...
CombinedCollection.Add(new SomeClass1())
CombinedCollection.Add(new SomeClass2())
.
.
.
//add more objects and do something about the collection
.
.
.

问题是:有没有可能有这样的收藏?如果可能，我该如何实现?如果不是，还有什么替代方法?

The question is: is it possible to have such collection? If it is possible, how can I achieve this? If no, what can be an alternative way?

推荐答案

这可以在 协方差和逆变.

添加一个新接口，使 T 参数协变(使用 out 关键字):

Add a new interface that and make the T parameter covariant (using the out keyword):

interface ISomeRow<out T> where T : RowBase
{
}

SomeBase 应该像这样继承该接口:

SomeBase should inherit that interface like this:

class SomeBase<T> : ISomeRow<T> where T : RowBase
{
    //some other properties and abstract methods
}

然后，以下将起作用:

List<ISomeRow<RowBase>> myList = new List<ISomeRow<RowBase>>();
myList.Add(new SomeClass1());
myList.Add(new SomeClass2());

希望这就是你要找的 :)

Hope this is what you're looking for :)

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