Thanks for providing the reproduction steps. I've had a look around the source and it seems like the problem is happening somewhere between CompilerHelpers.cs<https://github.com/IronLanguages/main/blob/master/Runtime/Microsoft.Dynamic/Generation/CompilerHelpers.cs#L368> and PythonBinder.cs<https://github.com/IronLanguages/main/blob/master/Languages/IronPython/IronPython/Runtime/Binding/PythonBinder.cs#L85>that calls it. If the interface is not visible, it tries to return it's base type which is null. If I just return the interface out of the GetVisibleType method before it hits null, the message is displayed as intended.
It seems logic is needed to special case interfaces and/or handle the PrivateBindings option but I don't know enough to say. Richard On Sun, Jan 9, 2011 at 4:42 AM, Leo Carbajal <des...@gmail.com> wrote: > Sorry to spam the list, but I did some more tracking on this and figured > something out. I downgraded from 2.7b1 to 2.6.2 and my original example > worked just fine in. I thought my woes were over, and then I ran into a > similar problem in 2.6.2. It appears that IPy cannot cast an object to a > different type, specifically an interface in 2.6.2, when the class is > internal and you're working with PrivateBinding = true > > I logged it as http://ironpython.codeplex.com/workitem/29939 with the > following example: > > internal interface IExample > { > string Message { get; set; } > } > > internal class Avatar : IExample > { > public string Message { get; set;} > > public Avatar() > { > Message = "I am an avatar."; > } > > public void Hello(Avatar avatar) > { > Console.WriteLine("From Hello: " + Message); > } > > public void Hi(IExample avatar) > { > Console.WriteLine("From Hi: " + Message); > } > } > > Using the following python code: > avatar = Avatar() > avatar.Hello(avatar) > avatar.Hi(avatar) > > avatar.Hello prints it's message as expected, but avatar.Hi fails with: System > Error: object reference not set to instance of object. > > On Sat, Jan 8, 2011 at 6:07 PM, Leo Carbajal <des...@gmail.com> wrote: > >> Ok, here's a clarification. >> >> Say you have this class: >> >> internal class ZMPReporter : IReporter >> { >> public string Setting { get; set; } >> >> internal void Trixery(string mes, string mes1, string mes2, bool >> thing) >> { >> Flash(mes, mes1, mes2, thing); >> } >> >> public void Flash(string sender, string message, string recipient, >> bool isAuthor) >> { >> ... >> } >> } >> >> It's a property of another class. In C# I would use it as follows: >> caller.Reporter.Flash(..parameters..) >> >> If I call it in a normal IPy engine it fails to even recognize the caller >> variable, which is fine and totally expected (and desired). In the >> PrivateBinding scenario described I can call >> >> caller.Reporter.Setting and get the text data perfectly. When I try to >> call caller.Reporter.Flash(), though, I get the System Error: object >> reference not set problem. However, I can call >> caller.Report._ZMPReporter__Trixery() just fine, which in turn calls Flash >> for me. >> >> I don't mind using the name mangling overly, but I do mind having to make >> internal proxies for perfectly good, already existing, functions. I can't >> just make those methods internal because the IReporter interface demands >> that they be public. If this was the only class that might give me problems >> I might even look for a way around that, but the entire project uses >> Interfaces extensively. >> >> On Sat, Jan 8, 2011 at 5:36 PM, Leo Carbajal <des...@gmail.com> wrote: >> >>> Hello all, >>> >>> Almost I thought I could have my cake and eat it too. I have a large >>> client-server project written in C# that I wanted to be able to script with >>> IronPython. The biggest requirement was that I wanted external admins to be >>> able to provide scripts for the server to augment its functions. However, I >>> don't want them to have full access to the server API so I resigned myself >>> to write the project with everything Internal and then build public facing >>> classes for the functionality I wanted to expose. This, I know, to work >>> fine. >>> >>> however, I still want to be able to use scripts on the server myself, for >>> other things. I ended up using two engines, one with PrivateBinding on and >>> one without. The one with PrivateBinding set to true can see all private and >>> internal members but whenever I try to call a function from IronPython I get >>> an exception of "System Error: Object reference not set to an instance of an >>> object." It's weird because I can call on properties and get their values, >>> but not functions. If I do a dir() on the class, and the member, IronPython >>> can clearly see what they are and that they exist. If it helps, the class >>> i'm trying to access is internal but has all public members (for >>> interfaces). >>> >>> I guess my question is whether this behavior is intentional or not. Being >>> able to use my API on one engine for actual server work while providing a >>> different one for plugin\event hook writers, would help tremendously. >>> >> >> > > _______________________________________________ > Users mailing list > Users@lists.ironpython.com > http://lists.ironpython.com/listinfo.cgi/users-ironpython.com > >
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