Is this some kind of referencing problem? Value not sticking - vb.net

Question

Apologies for the appalling title.
I have mocked up this code to mimic an issue I was encountering on a project.
I want to know why the property status does not 'stick'. Stepping through the code I can even see it setting the property!
Is it something to do with Structure being a value type?
Here is the code, it is standalone.
Imports System.Diagnostics
Public Class clsTest
Public Shared Sub test()
Dim myHolder As New holder
myHolder.info = New info(5)
With myHolder.info
Debug.Print("Initialised Status : {0}", .status)
Debug.Print("Initialised Original Status : {0}", .originalStatus)
myHolder.setStatusToTen()
Debug.Print("Next Status : {0}", .status)
Debug.Print("Next Original Status : {0}", .originalStatus)
End With
End Sub
End Class
Public Class holder
Private _heldInfo As info
Public Property info() As info
Get
Return _heldInfo
End Get
Set(ByVal value As info)
_heldInfo = value
End Set
End Property
Public Sub setStatusToTen()
_heldInfo.status = 10
End Sub
End Class
Public Structure info
Private _iOriginalStatus, _iStatus As Integer
Public Sub New(ByVal iStartingStatus As Integer)
_iOriginalStatus = iStartingStatus
End Sub
Public ReadOnly Property originalStatus() As Integer
Get
Return _iOriginalStatus
End Get
End Property
Public Property status() As Integer
Get
Return _iStatus
End Get
Set(ByVal value As Integer)
_iStatus = value
End Set
End Property
End Structure
When I run clsTest.test I get the following output-
clsTest.test
Initialised Status : 0
Initialised Original Status : 5
Next Status : 0
Next Original Status : 5
...even though setStatusToTen is doing exactly what it says on the tin!

Answer 1

This is yet another case of mutable structs being evil. Avoid using structures for this purpose. As a reference:
Why are mutable structs “evil”?

Answer 2

Yes, its because Structures are value types. When a struct object is assigned to another struct object, the full content of the struct is copied and duplicated. (See this C# example)
So in your code, this set:
Set(ByVal value As info)
_heldInfo = value
End Set
... effectively results in two copies of the structure being made. One is internal to holder and is represented by _heldInfo, and the other is 'external' to holder, and is represented by myHolder.info. After the copy has been made, when you set values on one of them, the other is not affected.
If you add this method to holder:
Public Sub printStatus()
Debug.Print("Internal Status : {0}", _heldInfo.status)
End Sub
... you will find where your value of 10 went.