Best way to create instance of child object from parent object

Question

I\'m creating a child object from a parent object. So the scenario is that I have an object and a child object which adds a distance property for scenarios where I want to s

Answer 1

There are libraries to handle this; but if you just want a quick implementation in a few places, I would definitely go for a "copy constructor" as previously suggested.

One interesting point not mentioned is that if an object is a subclass, then it can access the child's private variables from the within the parent!

So, on the parent add a CloneIntoChild method. In my example:

• Order is the parent class
• OrderSnapshot is the child class
• _bestPrice is a non-readonly private member on Order. But Order can set it for OrderSnapshot.

Example:

public OrderSnapshot CloneIntoChild()
{
    OrderSnapshot sn = new OrderSnapshot()
    {
        _bestPrice = this._bestPrice,
        _closed = this._closed,
        _opened = this._opened,
        _state = this._state       
    };
    return sn;
}

NOTE: Readonly member variables MUST be set in the constructor, so you will have to use the child constructor to set these...

Although I don't like "up-sizing" generally, I use this approach a lot for analytic snapshots...