How to Set MasterPage Variables from Content Page

Need to send information from your content page to your master page?
Despite what you may have read on a couple blogs, IT CAN BE DONE!
Here's how.

Suppose I have a variable in my code behind my master page that I want to set based on what content page is opened. In my particular case, I'm going to use an example of a menu that I will only show while browsing certain pages in my website.

The first thing I need to do is create a variable within my master page:
Private _showMenu As Boolean = False

I can use this variable later within my master page's Me.Load function to set the menu control to visible or not. Now, I need a way to interact with the Master page for this variable, so I will make a simple Property for the page:

Public Property ShowMenu() As Boolean

Get

Return _showMenu

End Get

Set(ByVal value As Boolean)

_showMenu = value

End Set

End Property

We are now done with the MasterPage, which for my example I have named "MyAwesomeMasterPage". Moving on to content pages, for each page I want to communicate with my master page, all I have to do is add one easy line in the initialization of the page. I do it so early, just in case I need to access the variable early in my master page's loading.

Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init

CType(Master, MyAwesomeMasterPage).ShowMenu = True

End Sub

By casting my content page's masterpage as the MyAwesomeMasterPage page that I created, it is now aware of the Public Property that I created for it.