strange problem when casting

[Can I]

hello,

I'm creating an instance of ShoppingCart class when session starts:

<%@ Import Namespace="Code.business.shopping_cart" %>
...
Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)
        ' Code that runs when a new session is started
        Session("shoppingCart") = New ShoppingCart()
    End Sub

and using it in my ShoppingCart Web Control

Imports Code.business.shopping_cart
...
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim shoppingCart As Code.business.shopping_cart.ShoppingCart = Session("shoppingCart")
        ...
    End Sub

and that works fine, but when I don't use fully qualified class name, like this:

Dim shoppingCart As ShoppingCart = Session("shoppingCart")

I'm getting class cast exception:

Unable to cast object of type 'Code.business.shopping_cart.ShoppingCart' to type 'ShoppingCart'.

isn't it odd?

 

[JohnH]

Types are assembly specific. If you for example have declared the "same" class in both a webservice and a windows application that consumes it you can't cast a returned webservice instance to the local version, they will per definition be differerent types. One solution is to declare the class in a commonly referenced class library (that way both will use the same assembly qualified type) or make the webservice defined class public and qualify that from the local consumer.