C# 接口 function 返回 class 取决于实现的位置

Question

I would like to have a Interface that depending on what class implements it, a function that the interface declares should return a specific class.

should i use something like this?

public interface IMyInterface
{
    T returnClassInstance();
}

and how should it look when i want to implement it into the classes?

public class MyClass : IMyInterFace
{
    public T returnClassInstance()
    {
        ClassInstance class = new ClassInstance();
        return (T)class;
    }    
}

What is the best approach to something like this?

Answer 1

You can use generics in interfaces -

public interface IMyInterface<T>
{
    T returnClassInstance();
}

And while implementing this interface in class, just use the specific class in generic

public class MyClass : IMyInterface<ClassInstance>
{
    public ClassInstance returnClassInstance()
    {
        ClassInstance obj = new ClassInstance();
        return obj;
    }
}

Answer 2

Generics

public interface IMyInterface<T>
{
    T returnClassInstance();
}

public class MyClass : IMyInterFace<ClassInstance>
{
    public ClassInstance returnClassInstance()
    {
        ClassInstance class = new ClassInstance();
        return class;
    }    
}

Answer 3

You can declare it like so:

public interface IMyInterface<T>
{
    T ReturnClassInstance();
}

and implement it:

public class MyClass : IMyInterface<MyClass>
{
    public T ReturnClassInstance()
    {
        return this;
    }
}

Answer 4

You are looking for the Class Factory pattern. Here is a good CodeProject article about it.