Does setting an object to nothing also set it's child objects to nothing? - oop

Question

Say I have an object, Email, one of whose properties is an object called EmailSkinner.
The EmailSkinner is instantiated in the class_initialize subroutine like this.
private sub class_initialize()
set EmailSkinner = new MyEmailSkinner
end sub
Must I explicitly set the EmailSkinner object to nothing in the class_terminate subroutine of Email?
private sub class_terminate()
set EmailSkinner = nothing
end sub
Or does this happen automatically when I set the Email object itself to nothing?

Answer 1

This is an interesting question. Your assumption is correct any object's you instantiate inside the scope of the parent class will be released when the parent class is released from memory.
However as with all object instantiation in VBScript (and by extension Classic ASP) there is nothing wrong with explicitly releasing objects using the Class_Terminate event.
Remember though that "scope" is important here.
If your EmailSkinner object reference is declared outside of the parent class (regardless of whether it is instantiated inside the class) the reference will remain and will require Class_Terminate() to force the object reference to be released.
Examples
Object Reference is declared inside Class scope.
Class ParentObject
Private _ChildObject
Private Sub Class_Initialize()
Set _Object = new ChildObject()
End Sub
End Class
Object Reference is declared outside Class scope (wouldn't recommend this approach).
Dim GlobalObject
Class ParentObject
Private Sub Class_Initialize()
Set GlobalObject = new ChildObject()
End Sub
'GlobalObject reference will remain so we need to
'force it to be released.
Private Sub Class_Terminate()
Set GlobalObject = Nothing
End Sub
End Class

Answer 2

By default, Class objects are auto destroyed, but if you create new objects outside, you will need to release them from memory .
Is always recommended that we clean memory in all scenarios .
I made a small piece of code for you to test ( I hope this would be similar to what you are trying to explain, since you didn't show us your code ) .
This code help us to check if something remains in memory after some steps of execution and declaration ( just take out the apostrophes at bottom to test the code ) :
Class EmailSkinner
public color
public size
Private Sub Class_Initialize
color = "blue"
size = 300
End Sub
End Class
Class Email
public details
public name
Private Sub Class_Initialize
Set details = New EmailSkinner '//Module Scope
End Sub
Private Sub Class_Terminate
Set details = Nothing
End Sub
End Class
Set email1 = New Email '//Global Scope
With email1
.details.color = "black"
.details.size = 400
End With
''//Take out the apostrophe to test one of the next lines
'Response.Write email1.details.color '//ASP only
'wscript.echo email1.details.color '//Wscript only
Set email1 = Nothing