Question

I have an interface I with two methods func A and func B and a class C with the implementation of the interface, I have two users U1 and U2.
I want the functionality so that if u1 accesses class C, func A should be called and if u2 accesses class C func B should be called.
How do i implement this using OOPs ?

Answer 1

I will focus on what you’ve asked. Why you would want to do this and whether it’s actually a good idea with respect to OO design principles is another question.

First, your requirement would look similar to the following: ^(note)

interface I
{
    void A();
    void B();
}

// class C : I { ... }

Now, let’s create a User role and two implementations for user 1 and user 2:

public interface User
{
    void Access(I x);
}

class User1 : User
{
    public void Access(I x)  {  x.A();  }
}

class User2 : User
{
    public void Access(I x)  {  x.B();  }
}

Finally, instantiate your users 1 and 2 as follows:

User u1 = new User1();
User u2 = new User2();

And “access” your C as follows:

I c = new C();
u1.Access(c);    // will call c.A()
u2.Access(c);    // will call c.B()

Note that this code almost completely leaves class C out of the game and instead focuses on the interface (I). If, however, you want your code to work specifically with C, simply replace I with C in the appropriate place (namely, with the parameter of method Access).

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^(note:) I’ve chosen C# for the examples, but translating to the language of your choice should be easy.