Can I make methods visible to some classes but not others - vba

Question

Quite simple; I've made a class with a method that's public since another class calls this method.
I would like the method only to show up on intellisense in the 2nd class which holds some special reference to the 1st one. Any other class or module should not be able to see the method.
Something along the lines of
Semi-Private (except for Class2) Sub ...
in the method of Class1, or in Class2
Can See Semi-Private methods of Class1

Answer 1

Instead of getting complicated with it, and using a roundabout approach, just use the tools meant for the job:
Class Module IFoo
Public Sub Bar()
' Interface methods are empty
End Sub
Class Module Foo
Private Type TFoo
Baz As String
End Type
Private this As TFoo
Implements IFoo
Private Sub Class_Initialize()
this.Baz = "I am a class that implements IFoo."
End Sub
Private Sub IFoo_Bar()
' Do Something
Debug.Print this.Baz
End Sub
Module Baz
Sub RunBaz()
Dim MyFoo As IFoo
' Note that this WILL NOT work. Nothing happens.
Set MyFoo = New IFoo
Debug.Print MyFoo.Bar
' Set MyFoo to be equal to a Foo (which implements IFoo)
Set MyFoo = New Foo
Debug.Print MyFoo.Baz
End Sub
This makes the methods only visible when the methods are being accessed through an interface which makes them public. Therefore, in order to use the methods in Foo we must first create an instance of Foo using an IFoo variable type.
Then, it is as simple as creating a new class which creates a Foo from an IFoo for its own use.
Class Module IImportantWorker
Public Sub DoSomethingImportant()
End Sub
Class Module ImportantWorker
Private Type TImportantWorker
Implementation As IFoo
End Type
Private this As TImportantWorker
Implements IImportantWorker
Private Sub Class_Initialize()
Set this.Implementation = New Foo
End Sub
Public Sub IImportantWorker_DoSomethingImportant()
this.Implementation.Bar
End Sub
You could get fancy from here and make a property of Foo that is exposed by IFoo that tells it whether or not it can work. This would have to be exposed through the IFoo interface (or, alternatively a separate interface so that the two interfaces must be used in conjunction).
Without locking the class (which I wouldnt recommend anyways, it seems foolish and pointless) Foo will still allow Bar if it is created as a IFoo. But if you just make Foo = New Foo then Foo will do nothing (or rather, expose nothing).
For additional resources, I highly recommend reading these excellent posts that go into greater depth about the processes:
Is VBA an OOP language, and does it support polymorphism?
https://rubberduckvba.wordpress.com/2016/06/16/oop-vba-pt-1-debunking-stuff/
https://rubberduckvba.wordpress.com/2016/07/05/oop-vba-pt-2-factories-and-cheap-hotels/

Answer 2

You may create the class that contains all properties and methods, name it BigClass:
Option Explicit
Dim i1 As Integer
Dim i2 As Integer
Dim i3 As Integer
Property Let var1(v As Integer)
i1 = v
End Property
Property Get var1() As Integer
var1 = i1
End Property
Property Let var2(v As Integer)
i2 = v
End Property
Property Get var2() As Integer
var2 = i2
End Property
Property Let var3(v As Integer)
i3 = v
End Property
Property Get var3() As Integer
var3 = i3
End Property
Then you can make classes that inherits BigClass methods, but not necessary all of them. For example, SmallClass1 that will use only var3 variable.
Option Explicit
Dim BigOne As BigClass
Private Sub Class_Initialize()
Set BigOne = New BigClass
End Sub
Private Sub Class_Terminate()
Set BigOne = Nothing
End Sub
Property Let var3(v As Integer)
BigOne.var3 = v
End Property
Property Get var3() As Integer
var3 = BigOne.var3
End Property
Then you can create SmallClass2 that use var2 and var1 but not var3. You get the point.

Answer 3

An clear example would be involved and lengthy and I have deposited one on my blog here VBA - Difference between Friend and Public with inter project references.
Essentially you use the Friend keyword but nothing happens until you split your code across workbooks which itself brings issues such as Instancing and factory functions. Example given should work though. Enjoy!