I have something like the following situation below:
class Base
{
public static int x;
public int myMethod()
{
x += 5;
return x;
}
}
class DerivedA : Base
{
}
class DerivedB : Base
{
}
I am trying to set this up so that each derived class has its own static instance of x, if I do something like this:
DerivedA.x = 5;
DerivedB.x = 10;
then when I run:
DerivedA.myMethod(); //The result will be 10
DerivedB.myMethod(); //The reusult will be 15
Can i do something like this? How can I setup the derived classes to achieve this? Thanks guys.
EDIT: Basically, I have a bunch of derived classes that each have a property unique to that class. It does not vary for each instance, and thus I believe should be a static variable. Also, that property is set by a method, that is the same for each of these classes. I am trying to avoid having to copy and paste the logic for that property and method in each of these derived classes. I thought it best to somehow move that logic to the base class from which each of these classes are derived from. But, I need each derived class to have its own copy of that property. I do not necessarily have to do it this way, and I will be happy to hear some better practices suggestions if you guys have any.. Thanks!
Well, yes, you can, but it revolves around a bit of a trick with generics.
It is much better if you fix your design so that you don't need that static field, or at least not per descendant, but here goes:
class Base<TDescendant>
where TDescendant : Base
{
public static int x;
public int myMethod()
{
x += 5;
return x;
}
}
class DerivedA : Base<DerivedA>
{
}
class DerivedB : Base<DerivedB>
{
}
This relies on the fact that a generic type with static fields will get a separate copy of those static fields for each type you invoke it with.
However, if you intend to descend from DerivedA or DerivedB, it gets tricky, so I wouldn't recommend going down this lane.
You will need to redefine and hide the field and method in all derived types.
Example:
class DerivedA : Base
{
public new static int x;
public new int myMethod()
{
x += 5;
return x;
}
}
Note: don't do it this way. Fix your design.
Edit:
Actually, I have a similar construct. I solve it with an abstract (if you need a default value, use virtual
) property which then gets used from the base class:
public abstract class Base
{
public abstract string Name { get; }
public void Refresh()
{
//do something with Name
}
}
public class DerivedA
{
public override string Name { get { return "Overview"; } }
}
You should be able to adjust that for your use case. You can of course make the property protected
if only deriving classes should be able to see it.
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