Thanks for digging into it. A fix in the next release will be fine. Rather than recompile IP, I worked around it by writing a C# class that overrides the property.
-----Original Message----- From: Dino Viehland [mailto:[EMAIL PROTECTED] Sent: Thursday, April 26, 2007 4:45 PM To: Discussion of IronPython Subject: Re: [IronPython] can't override LayoutEngine property Wow, after digging into this some more I gotta say: this is very interesting and may be a CLR bug. The short of this is there's a bug here and there's at least a work around (from the perspective of you can rebuild IronPython :) ). In Src\IronPython\Compiler\Generation\NewTypeMaker.cs there's a function called OverrideSpecialName. It's signature needs a new parameter: private void OverrideSpecialName(Type type, MethodInfo mi, Dictionary<string, bool> specialNames) { and then that parameter needs to be used for the GetProperties call: PropertyInfo[] pis = type.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); There's 1 caller to this function in OverrideVirtualMethods and it just needs to pass type: OverrideSpecialName(type, mi, specialNames); Here's an explanation of what's going on. We are calling GetMethods() on Panel which returns the methods for Panel and all of its subtypes - including Control. We are then filtering those down to virtual methods and trying to find the property they are associated with. At that point in time we call GetProperties() on the method's declaring type (in this case, Control) to get all of the properties. We then go through each property trying to find the property who has a get or set method that matches this method (get_LayoutEngine). What's strange is that we come to a point where we have a get_LayoutEngine method declared on Control that we grabbed from Panel, and we have a get_LayoutEngine method declared on Control that we grabbed from Control's LayoutEngine property. For some reason these two methods aren't comparing equal even though they're the exact same method. Given that we have a workaround for IronPython I'll open a bug (9908 - http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=9908) and this should go into the next stable release. I'll also follow up with the CLR team and see if they believe this is a bug and if so get that fixed as well. Thanks for reporting this... Hopefully the workaround won't be too much trouble until we get the next release out. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jonathan Amsterdam Sent: Thursday, April 26, 2007 12:23 PM To: users@lists.ironpython.com Subject: Re: [IronPython] can't override LayoutEngine property Dino, Thanks for your prompt reply. Unfortunately, your suggestion doesn't work either (it gives the same result when invoked from C#). Moreover, the first way (name = property(...)) worked fine when I just built my own C# class with its own virtual property. Date: Thu, 26 Apr 2007 11:04:08 -0700 From: Dino Viehland <[EMAIL PROTECTED]> Subject: Re: [IronPython] can't override LayoutEngine property To: Discussion of IronPython <users@lists.ironpython.com> Message-ID: <[EMAIL PROTECTED] .microsoft.com> Content-Type: text/plain; charset="us-ascii" I believe currently you need to do: @property def get_MyLayoutEngine(self): return mle to get the get_ method to override this. A couple of people have ran into this and we don't seem to have a bug on it so I've opened bug #9902 (http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=9902) to make this more intuitive. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jonathan Amsterdam Sent: Thursday, April 26, 2007 8:23 AM To: users@lists.ironpython.com Subject: [IronPython] can't override LayoutEngine property I'm trying to overrride the LayoutEngine property of Control so I can implement my own layout engine. I find that this doesn't work in IP. Accessing the LayoutEngine property in IP works fine, but it doesn't work from C#. //////////////////// C# code: public class MyCSharpClass { public static LayoutEngine getLayoutEngine(Panel p) { return p.LayoutEngine; } } //////////////////// Python code: class MyLayoutEngine(LayoutEngine): def Layout(self, parent, eventArgs): pass mle = MyLayoutEngine() class MyPanel(Panel): LayoutEngine = property(lambda self: mle) p = MyPanel() print "from Python:", p.LayoutEngine print "from C#:", MyCSharpClass.getLayoutEngine(p) //////////////////// output: from Python: <MyLayoutEngine object at 0x000000000000002B> from C#: System.Windows.Forms.Layout.DefaultLayout ======================================================================== ===================== Email transmissions can not be guaranteed to be secure or error-free, as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. 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