如何仅对一个班级的3个孩子实施一种非静态方法？

Question

I have 7 classes which inherit the "Base" class :

• Base
• Class1 : Base
• Class2 : Base
• ...
• Class7 : Base

For 3 of these 7 classes, I have to add a non-static method (exactly the same code), but this method should not be visible for the others classes, and I don't know how to organize my code.

Anybody can help me ?

Edit : I can't do like this :

• Base
  • Class with 'secret' method : Base
  • Class1 : Class with 'secret' method
  • Class2 : Class with 'secret' method
  • Class3 : Class with 'secret' method
  • Class4 : Base
  • Class5 : Base
  • Class6 : Base
  • Class7 : Base

Because in the non-static method, I use an attribute which is declared in the Class1, Class2 and Class3 classes (and I can't move it, it's handled by Entity Framework). Example :

this.var

Answer 1

Do it like so:

• Base
  • Class with 'secret' method : Base
    • Class1 : Class with 'secret' method
    • Class2 : Class with 'secret' method
    • Class3 : Class with 'secret' method
  • Class4 : Base
  • Class5 : Base
  • Class6 : Base
  • Class7 : Base

Answer 2

There are more ways to reuse code than inheritance. Inheritance should only be used when you need an "is-a" type, not simply because you don't want multiple copies of code.

Containment might be a better choice. But, it depends on what exactly your method does.

For instance:

public class Contained {
    public void SpecialMethod() {}
}

public class Class1 : Base {
    private Contained _contained = new Contained();

    public override void NormalMethod() {
        // do some work
        _contained.SpecialMethod();
    }
}

public class Class2 : Base {
    private Contained _contained = new Contained();

    public override void NormalMethod() {
        // do some work
        _contained.SpecialMethod();
    }
}