CODEWITHSUNDEEP
c#overridingclass-design
Raghav55
Raghav55

Reputation: 3135

Restricting subclasses from inheriting certain methods of base class

using System;

public class Base
{
    public Base()
    {
    }

    public void M1()
    {
    }

    public void M2()
    {
    }

    public void M3()
    {
    }
}

public class Derived : Base
{
    //this class should get only method 1
}

public class SecondDerived : Base
{
    //this class should get only method 2 and method3
}

The requirement is : the base class contains the 3 methods M1, M2, M3.
The derived class should inherit only M1 and SecondDerived should inherit only M2 and M3.

How can this be done?

Upvotes: 1

Views: 1480

Answers (4)

Venom
Venom

Reputation: 1106

It is possible by adding Obsolete attribute 

public class A
{
    public virtual void M1() { }
    public void M2() { }
    public void M3() { }
}

public class B : A
{
    [Obsolete("You can not use this", true)]
    public sealed override void M1()
    {

    }
}

public class C : B
{
    public void Test()
    {
        // Will show error 
        base.M1();

    }
}

Upvotes: 0

InBetween
InBetween

Reputation: 32750

It is not possible to do what you want with inheritance.

It seems you have no intention of overriding, you simply want to "inherit" behavior from the base class selectively. You could do this using a "has a" relationship:

public class Base
{
     internal Base() {} //mark constructor as internal so it can not be used outside your assembly if necessary

     public Foo Mehtod1() {...}
     public Foo Mehtod2() {...}
     public Foo Mehtod3() {...}
}

Then simply do the following:

class A
{
     private Base internalBase;

     public A() { this.internalBase = new Base(); }

     public Foo Method1() { return this.internalBase.Method1(); }
}

class B
{
     private Base internalBase;

     public A() { this.internalBase = new Base(); }

     public Foo Method2() { return this.internalBase.Method2(); }
     public Foo Method3() { return this.internalBase.Method3(); }
}

UPDATE: A possible alternative solution is to make your Base class methods virtual and override them all in your derived classes, throwing NotSupportedExceptions in those methods that you do not want the class to make available. I don't really like this solution but it has the advantage of not loosing the polyphormism inheritance gives you which might be useful if you have some core base functionality which all derived classes will share (in your example you seem to imply they wont).

Upvotes: 0

Henk Holterman
Henk Holterman

Reputation: 273229

You cannot do it in this way. Inheritance implies an "IS A" relationship.

If SecondDerived would not have a M1() then it would not be compatible with a reference to a the class Base.

So maybe you shouldn't be using inheritance for whatever problem you're solving.

Upvotes: 3

Tudor
Tudor

Reputation: 62439

You cannot selectively inherit methods like this. A derived class automatically inherits all public methods of the base class. I suggest you to split the Base class into two classes:

public class Base1
{
    public Base1()
    {
    }

    public void M1()
    {
    }
}

public class Base2
{
    public void M2()
    {        
    }

    public void M3()
    {       
    }
}

public class First : Base1

public class Second : Base2

Upvotes: 3

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