仅在一个类中设置泛型类型

Question

I have two generic classes:

public class First<T>
{
    ...
}
public class Second<T>
{
    ...
}

I use Second class as parameter for First class constructor:

var instance = new First<int>(new Second<int>());

Is it possible to specify generic type (integer in my example) only for First class constructor like this:

var instance = new First<int>(new Second());

?

Answer 1

我相信通用构造函数参数的类型推断正被添加到C＃6中。现在，答案是否定的。

Answer 2

This is my workaround suggestion, which gives you a nice syntax.

public class First
{
    public static First<T> Create<T>(Second<T> second)
    {
        return new First<T>(second);
    }
}

public class First<T>
{
    public First(Second<T> second)
    {

    }
}
public class Second<T>
{

}

Use it like this:

var instance = First.Create(new Second<int>());

Answer 3

This is a trick that could work: (Whether or not it is good practice, I'll leave to you)

public class Second { }

Inside the Second<T> class:

public static implicit operator Second<T>(Second second) {
    return new Second<T>();
}

This will only work if the First<T> constructor ONLY accepts Second<T> and not another Second<U> or something.