Abstract class > mandatory constructor for child classes [duplicate]

Question

Possible Duplicate:
Why can’t I create an abstract constructor on an abstract C# class?

How can I write one abstract class that tells that is mandatory for the child class to have one constructor?

Something like this:

public abstract class FatherClass
{

    public **<ChildConstructor>**(string val1, string val2)
    {

    }

   // Someother code....
}

public class ChildClass1: FatherClass
{
    public ChildClass1(string val1, string val2)
    {
       // DO Something.....
    }
}

UPDATE 1:

If I can't inherit constructors. How can I prevent that someone will NOT FORGET to implement that specific child class constructor ????

Answer 1

You cannot.

However, you could set a single constructor on the FatherClass like so:

protected FatherClass(string val1, string val2) {}

Which forces subclasses to call this constructor - this would 'encourage' them to provide a string val1, string val2 constructor, but does not mandate it.

I think you should consider looking at the abstract factory pattern instead. This would look like this:

interface IFooFactory {
    FatherClass Create(string val1, string val2);
}

class ChildClassFactory : IFooFactory
{
    public FatherClass Create(string val1, string val2) {
        return new ChildClass(val1, val2);
    }
}

Wherever you need to create an instance of a subclass of FatherClass, you use an IFooFactory rather than constructing directly. This enables you to mandate that (string val1, string val2) signature for creating them.