How to get to a data object of class A from Class B (not from the main class)

Question

Let's say I have 3 classes:

Main class, class A, class B

and let's also say that class B has a method which needs data from class A. (the data is actually a dataview object).

objects instances of class A and class B are created in the main class regardless of the above (for them to be created in general)

what would be the best way to reach the dataview object of class A from class B?

Should I make the dataview object internal? should I make it static? should I make it internal static?

I've learned to create properties in cases like these and just "get" the object, but since it's the main form (and not Class B) which creates an object of Class A, I can't reach that property from class B.

---

Edit, here is a demo code:

Class Main
{

A a = new A();
B b = new B();

a.doingAClassStuff(); //Not possible unless Class A is set to public or the method is set to internal (classes are internal by default)
b.doingBClassStuff(); //Likewise

//need to get the dv object here.
//dv.rows[1].foo = bar;
}

Here above in the main class I need to get the dv object from Class B.

//each class exist in a different class file (.cs file) inside the project
Class A 
{
doingAClassStuff()
{
MessageBox.Show("Hello From Class A!");
}
//here access to the dv object is also needed.
//dv.rows[5].foo = something;
}

Class A also needs to get the dv object of Class B!

//in another file as well
Class B 
{
DataView dv = new Dataview(datatable1)

doingBClassStuff()
{
MessageBox.Show("Hello From Class B!");
}
}

My notes:

1. Making "dv" only "Internal" will not make it visible.

2. Making "dv" "Internal Static" will make it visible and I can work with that but I am not sure "static" has no Cons, I am not creating more than 1 instance of each class (if it matters).

3. I tried setting properties with "get" and get it but since the properties are public and I couldn't set them to "internal" are they public to outside of the assembly as well?

Many Thanks!

Answer 1

Without any additional information in regards to your requirements and restrictions, this is how I would handle it.

If you need Class A for a Class B to operate properly, you should probably provide Class B with a Class A member and either initialize it in the constructor for Class B or provide a method to set the member.

Class A should then expose through its public interface what Class B needs in a manner that makes sense for the class. i.e. don't just make the DataView public.

public class A
{
    private B _b;

    public A(B b)
    {
        _b = b;
    }

    void UseData()
    {
        _b.GetData();
    }
}

Public class B
{
    public DataView GetData();
}

elsewhere

B b = new B();
A a = new A(b);

Answer 2

I can't add a comment yet but this seems similar to the following post which asks for an equivalent to friend. The top answer says to use InternalsVisibleTo to achieve somewhat similar functionality.

What is the C# equivalent of friend?

Answer 3

what would be the best way to reach the dataview object of class A from class B?

Some options:

• Pass an instance of A to a method of an instance of B
• Add a property to B of type A (if the instance would be used for multiple operations

Should I make the dataview object internal? should I make it static? should I make it internal static?

• Make it internal if you want it accessible to all types within the same assembly but not outside of the assembly (basically private to the assembly

• Make it public if you want it available to all types inside and outside the assembly

• Make it static if the data would apply to all instances of A