参数未知的构造函数

Question

在我C#度过了大半生的生活之后,我最近开始做一些编程PHP.

在PHP我能做到这一点:

class User
{
    public __construct($UserId)
    {
        // Do stuff
    }
}

class Employee extends User
{
    public __construct($EmployeeId)
    {
        // Look up the UserId connected to $EmployeeId
        $UserId = hypothetical_get_user_id_func($EmployeeId);
        parent::__construct($UserId);
    }
}

但是,C#我似乎没有这种可能性,因为$UserId在它进入第一个构造函数之前,我似乎必须知道它.

public class User
{
    public User(int UserId)
    {
        // Do stuff
    }
}

public class Employee : User
{
    public Employee(int EmployeeId) : base(***) // I don't know this value yet?
    {
        // This is where I would find the User Id, and would like to pass
        // it to the User class constructor.
    }
}

有没有办法实现我在C#中尝试做的事情？

基本上将值传递给主对象的构造函数,主对象在自己的主体中指出要传递给基类的值.

Answer 1

您可以在构造函数中调用静态方法.虽然非常不标准.

public class User
{
    public User(int userId)
    {
        // Do stuff
    }
}

public class Employee : User
{
    public Employee(int employeeId) : base(GetUserId(employeeId))
    {

    }

    public static int GetUserId(int employeeId)
    {           
        return employeeId - 5;
    }
}