How to allow instanciation of a class from another class method inside the same assembly???

[Bob Rock]

Hello,

I'd like to be able to allow instanciation of a class (class Class_A) only
from another class method (class Class_B). And I'd like to write the
necessary code to enforce this behavior even inside the same assembly where
class Class_A and Class_B are defined.
I've written the code that does this BUT I'd like to understand if this is
the most correct way to obtain such a result.

This is my simplified code:

// abstract class
public abstract class Class_C
{
public abstract void Method_1();
}

public class Class_B
{
// method that returns instances of class Class_A
public Class_A Method_2()
{
return new Class_A();
}

// nested private class - implements the abstract class Class_C
private class Class_A : Class_C
{
public override void Method_1
{
// implementation code
}
}
}

The above implentation allows the writing of the following "client" code:

Class_B b = new Class_B();
Class_C c = b.Method_2(); // creating an instance of class Class_A
c.Method_1(); // calling Method_1() of class Class_A

This code works well, the only thing I don't like is that Class_A is
completely unknown by code outside class Class_B.
Instead of an abstract class I could have used an interface but, since I
won't need to implement that interface more than once, I thought using an
abstract class to hold a reference to an instance of class Class_A to be
more correct.

Can anyone review this approach and tell me if there is any better solution?
Bob Rock

[Bob Rock]

> yes well done! a protected constructor gets around this issue. The only

potential problem I can see with all this, is that if the ManagedClass has
public members, then they will be accessible through the ManagerClass
instance (because they will be inherited).
Anyway you seem to have got where you wanted so I'll sign off for now.

Mark there is no such issue.
The manager class DOES NOT inherit from the managed class, the private
nested class inside the manager class is inheriting.
Bob Rock

[Mark Broadbent]

sorry yes, didnt look at your code listing long enough, was still playing
with my code!
Anyway well done.
--

--

Br,
Mark Broadbent
mcdba , mcse+i
=============
"Bob Rock" <no************ *************** @hotmail.com> wrote in message
news:%2******** ********@tk2msf tngp13.phx.gbl. ..

yes well done! a protected constructor gets around this issue. The only
potential problem I can see with all this, is that if the ManagedClass has public members, then they will be accessible through the ManagerClass
instance (because they will be inherited).
Anyway you seem to have got where you wanted so I'll sign off for now.

Mark there is no such issue.
The manager class DOES NOT inherit from the managed class, the private
nested class inside the manager class is inheriting.
Bob Rock