名单 <T> ＆哪里T：

Question

I have simple code witch works ok:

public class Example
{

    private List<SomeClass> _list = new List<SomeClass>();

    public void Add(SomeClass _b) {
        _list.Add(_b);
    }

}

it possible to add SomeClass to _list something like this? (without specifying argument)?

public void Add<T>() where T : SomeClass
{

}

Answer 1

Assuming that SomeClass has a default constructor, you can:

public void Add<T>() where T : SomeClass, new()
{
    _list.Add(new T());
}

If SomeClass does not have a default constructor then you won't be able to write new T() and you will need to find another way of getting a T object.

Answer 2

You may use generics:

public class Example<T>
{
 private List<T> = _list = new List<T>();
 public void Add(T element)
 {
   _list.Add(element);
 }
}

Answer 3

What would you be adding? I don't see any point to that. The external consumer of Example would not be able to add anything.

Answer 4

You would have to do

public void Add<T>(T _b) where T : SomeClass
{

}

But it is pretty pointless and means the same thing as you existing code.