[IronPython] FW: FW: FW: returning inherited classes to .NET

Fri Feb 22 07:07:09 CET 2008

Thanks for your help so late Curt (not that I need a quick answer at
all).

I am sure I am missing something big-time here and "talking" as
cross-purposes, but, to my mind the reason I don't have a problem when
running from the command line is because all I am doing is running the
ipy.exe on the file which loads some assemblies, creates a class
definition and a function definition and then terminates without even
instantiating the class.  Is this what you mean by "running it
directly"?   

Thanks again,
Kyle

________________________________

From: users-bounces at lists.ironpython.com
[mailto:users-bounces at lists.ironpython.com] On Behalf Of Curt
Hagenlocher
Sent: Friday, 22 February 2008 4:55 PM
To: Discussion of IronPython
Subject: Re: [IronPython] FW: FW: returning inherited classes to .NET

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.NET makes 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 <
Kyle.Howland-Rose at aar.com.au> 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: users-bounces at lists.ironpython.com [mailto:
users-bounces at lists.ironpython.com] 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 <
Kyle.Howland-Rose at aar.com.au> 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: users-bounces at lists.ironpython.com

		[mailto:users-bounces at lists.ironpython.com] 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
		<Kyle.Howland-Rose at aar.com.au> 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

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<http://www.aar.com.au/> 

	This email is confidential and may be subject to legal or other
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