Question

Say, we have two classes:

public class A
{
    protected static readonly int DefaultValue = 123;

    int value;

    public A()
    {
        value = DefaultValue;
    }

    public A(int _value)
    {
        value = _value;
    }
}

public class B : A
{
    public B(XElement x)
        : base(x.Element("int") == null 
                  ? A.DefaultValue 
                  : (int)x.Element("int"))
    {
    }
}

I understand that I could make a parameterless constructor for class B::

public B():base()
{
}

and have smth like this:

B objB = (x.Element("int") == null)?new B():new B((int)x.Element("int"));

but I’d love to have this logic encapsulated in class B.

Also I see I can do some kind of static factory method and have it encapsulated (and even make those class B constructors private if necessary):

public static B GetInstance(XElement x)
{
    return (x.Element("int") == null)?new B():new B((int)x.Element("int"));
}

But I’d love to be able to have smth like the following pseudo code:

public class A
{
    //don't need this anymore 
    //protected static readonly int DefaultValue = 123;

    int value;

    public A()
    {
        value = 123;
    }

    public A(int _value)
    {
        value = _value;
    }
}

public class B : A
{
    public B(XElement x)
        : x.Element("int") == null
              ? base()
              : base((int)x.Element("int"))
    {
    }
} 

Or is there any other approach which could do the same thing as nice and even better?

Answer 1

Have you tried playing around with a null int (int?) in the Class A constructor? With a optional parameter you might be able get away with one constructor.