If you're only getting the error under ASP.NET, then it's highly likely that you're loading multiple copies of the same assembly, which is why the CLR can't cast your Python class back to the VB base -- it literally considers them to be two different classes. This may be related to the way ASP.NETmakes shadow copies of your files, but there could be other reasons as well (none of which, unfortunately, come to mind right now).
Using an interface instead of a base class would give you the same results. On Thu, Feb 21, 2008 at 9:44 PM, Howland-Rose, Kyle < [EMAIL PROTECTED]> wrote: > It runs fine from the command line but then it does not do much ... yet. > For the moment I am simplifying it by removing IP :( > > I wanted to so some moderately heavy reflection which to my thinking > should be easier from IP but I will use VB for now. > > I assume I *should* be able to return a derived python class to VB? > Alternatively I could implement an interface. How can IP implement a .NET > interface? > (All pointers to pre-existing doco warmly received :) > > Thanks > Kyle > > ------------------------------ > *From:* [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] *On Behalf Of *Curt Hagenlocher > *Sent:* Friday, 22 February 2008 4:29 PM > *To:* Discussion of IronPython > *Subject:* Re: [IronPython] FW: returning inherited classes to .NET > > My apologies; I wasn't reading the code correctly. That's probably a > sign that I should be going to bed. :) Have you tried simplifying your > version just a little bit by running it directly rather than through > ASP.NET <http://asp.net/>? > > > On Thu, Feb 21, 2008 at 8:43 PM, Howland-Rose, Kyle < > [EMAIL PROTECTED]> wrote: > > > Hi Curt, > > > > Thanks for replying. When I view the link I see the following: > > > > The .NET code creates the "Test" class and then runs the python code > > which imports the "Test" class a subclasses it to create python class > > "X". > > > > Class "X" is then called and cast to type "Test" and assigned to the > > value obj. > > > > Is this what you are looking at? > > > > My code is pretty much identical. The VB looks like: > > > > > > Public MustInherit Class ChildControl > > Public Function Control() As WebControl > > Return Nothing > > End Function > > Public Function GetValue() As String > > Return Nothing > > End Function > > Public Function SetValue(ByVal value As Object) As String > > Return Nothing > > End Function > > End Class > > > > Class IPReflection > > Private Shared Instance As IPReflection = Nothing > > Private PyEngine As PythonEngine > > Private PyModule As EngineModule > > > > Public Shared Function Inst() As IPReflection > > If Instance Is Nothing Then > > Instance = New IPReflection > > End If > > Return Instance > > End Function > > > > Private Sub New() > > Dim path As String = HttpContext.Current.Request.MapPath(".") > > PyEngine = New PythonEngine > > PyEngine.AddToPath(path) > > PyModule = PyEngine.CreateModule > > PyEngine.DefaultModule = PyModule > > > > PyEngine.ExecuteFile(HttpContext.Current.Request.MapPath("CustomControls > > .py")) > > End Sub > > > > Public Function GetChildControl() As ChildControl > > Return > > CType(Operations.Ops.Call(PyModule.Globals("GetControl")), ChildControl) > > End Function > > End Class > > > > And the python looks like: > > > > import clr > > import sys > > > > clr.AddReference('System') > > import System > > > > sys.path.append(sys.path[0] + "/bin") > > > > clr.AddReferenceToFile("WebControlLibrary.dll") > > clr.AddReference('System.Web') > > > > from System.Web.UI.WebControls import Label > > > > from WebControlLibrary import ChildControl > > > > class LabelChildControl(ChildControl): > > def __init__(self): > > self.control = Label() > > def Control(self): > > return self.control > > > > def GetControl(): > > return LabelChildControl() > > > > > > Thanks again, > > Kyle > > > > ________________________________ > > > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Curt > > Hagenlocher > > Sent: Friday, 22 February 2008 3:08 PM > > To: Discussion of IronPython > > Subject: Re: [IronPython] returning inherited classes to .NET > > > > > > The page in question doesn't seem to show what you describe -- deriving > > a Python class from a C# class. Maybe you could show us your sample > > code? > > > > > > On Thu, Feb 21, 2008 at 7:39 PM, Howland-Rose, Kyle > > <[EMAIL PROTECTED]> wrote: > > > > > > Hi all, > > I am following > > > > > > http://www.ironpython.info/index.php/Using_Python_Classes_from_.NET > > <http://www.ironpython.info/index.php/Using_Python_Classes_from_.NET> > > but using VB. > > > > In VB I declare a class and derive a python 1.1 class from it > > but when I return it I get the exception: > > > > "Unable to cast object of type > > 'IronPython.NewTypes.WebControlLibrary.ChildControl_1' to type > > 'WebControlLibrary.ChildControl'." > > > > The page referenced above just seems to cast the python class > > instance to the C# class instance but this does not work for me in VB. > > > > Any help would be appreciated :) > > > > Thanks, > > > > Kyle > > > > > > > > > > ************************************************************************ > > > > Allens Arthur Robinson online: http://www.aar.com.au > > <http://www.aar.com.au/> > > > > This email is confidential and may be subject to legal or other > > professional privilege. 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