can I pass an aspx page class to a subroutine? - asp.net

Question

Here's what I'd like to do: Let's say I have a page named "foo.aspx". The class is called "foo". On the page is a checkbox named "bar". I want a subroutine to update that checkbox.
So what I want to write is something like:
In foo.aspx.vb:
partial class foo
... whatever ...
dim util as new MyUtility
util.update_checkbox(me)
In MyUtility
public sub update_checkbox(foo1 as foo)
foo1.bar.checked=true
end sub
But this doesn't work, as Visual Studio doesn't accept "foo" as a class name. Why not? Is there a magic namespace on it, or something else I have to do to identify the class besides say "foo"?
(And yes, I realize that in this trivial example, I could just pass in the checkbox, or move the one line of code into the aspx.vb, etc. My real problem involves setting a number of controls on the form, and I want to be able to do this in a class that has subtypes, so I can create an instance of the proper subtype, then just call one function and set all the controls differently depending on the subtype.)
Update
NDJ's answer works. For anyone else dropping by here, let me add that I was able to do something a little more flexible than his suggestion. I was able to create a property that returns the control itself, rather than some attribute of the control. Namely:
public interface ifoo
readonly property bar_property as literal
end interface
partial class foo
inherits system.web.page
implements ifoo
Public ReadOnly Property bar_property As Literal Implements ITest.bar_roperty
Get
' assuming the aspx page defines a control with id "bar"
Return bar
End Get
End Property
...
dim util=new MyUtility()
util.do_something(me)
...
end class
public class MyUtility
public sub do_something(foo as IFoo)
foo.bar_property.text="Hello world!"
foo.bar_property.visible=true
end sub
end class
This is a bit of a pain as you have to create an interface, and then create a property for each control that you want to be able to manipulate, but it does appear to work.
If there's a way to make the aspx class itself public, this is all unnecessary baggage in most cases. (It might be valuable if you have multiple pages that have controls that you want to manipulate in the same way.) But I can't figure out how to do that.

Answer 1

You can do this, but there are a few hoops to jump through.
Using your example...
If you create an interface with a Boolean property, then implement it in your page, then you can pass the interface about and changing the property will automatically change the checkbox. i.e.
interface:
Public Interface IFoo
Property Bar As Boolean
End Interface
implementation:
Partial Class _Foo
Inherits Page
Implements IFoo
Public Property Bar As Boolean Implements IFoo.Bar
Get
Return Me.CheckBox1.Checked
End Get
Set(value As Boolean)
Me.CheckBox1.Checked = value
End Set
End Property
Then some handler just needs to accept the interface:
Public Module SomeModule
Public Sub SetValues(foo As IFoo)
foo.Bar = True
End Sub
End Module
and the caller from the page passes itself:
Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
SomeModule.SetValues(Me)
End Sub

Answer 2

You can expose the checkbox as a public property on the page. I don't write in VB.net, but it would look something like this in C#:
Can someone convert this to VB.Net?
public bool MyCheckBoxSetting
{
get { return mycheckbox.Checked; }
set { mycheckbox.Checked = value; }
}