Question

I have 2 base classes FirstBase and SecondBase. I also have 2 class derive from them, DerivedFirst and DerivedSecode and both of them has almost of same property. Source code is like below.

public abstract class FirstBase
{
    //some method
}

public abstract class SecondBase
{
    //some method
}

public class DerivedFirst : FirstBase
{
    //override methods of its parent

    public static implicit operator DerivedFirst(DerivedSecond second)
    {
        //doing some logic here
    }
}

public class DerivedSecond : SecondBase
{
    //override methods of its parent

    public static implicit operator DerivedSecond(DerivedFirst first)
    {
        //doing some logic here
    }
}

From this code I can create instance of DerivedFirst and assign to DerivedSecond without any problem. However when I try to convert list of them like code below, It has no result.

List<DerivedFirst> firstList;
List<DerivedSecond> secondList;

//doing some operation here

List<DerivedSecod> test = firstList.Cast<DerivedSecond>(); // don't have any output here.

How can I convert firstList to List()?

Answer 1

User-defined implicit conversions are considered only at compile time, not at run-time (source). You can use Select instead:

List<DerivedSecond> foo = firstList.Select(x => (DerivedSecond)x).ToList();