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.NET 3.5 SP1 broke some scenarios for mixins

with 4 comments

OK, first, apologies for not posting for so long. The initial post was triggered by the Lang.NET symposium. We thought it might be a good idea to come forward with a part of our framework even prematurely, because Lang.NET might trigger enough interest. Seems that this did not happen, and since comments were rare, we decided to continue working on some refactorings, extensions and documentation we wanted to get ready before the real launch. Good news: We’re almost there.

SP1 bug for custom modifiers

The service pack that was released yesterday crashes when certain APIs for custom modifiers are called on generic methods of generic interfaces, like IWhatever<T>.Foo<U>().

Fabian posted a connect bug with details, votes are welcome.

Ayende Rahien has the exact same problem with RhinoMocks. Just like Ayende, a non-redistributable hotfix does not seem like much of a solution to us. Even a redistributable one would make the install experience quite cumbersome. I have no doubt that this would be fixed in the next release, but that’d take some time. A hotfix that gets distributed via Windows/Microsoft Update would be great, of course.

No idea what Microsoft can or will do for us here. However, unlike Ayende, we have no problem with using PSS, the risk of getting charged is not really a problem. But first, let’s give them a few days time to handle this via connect.

Here are our options:

  • Find another way to get custom modifiers. That would be great, but it’s quite unlikely that another .NET API, if it exists, would not result in the same situation within the CLR.
  • Use Cecil instead of Reflection. There are a few things we’d like to use Cecil for in the future, but this is not something that we’re going to do tomorrow.
  • Do nothing and have the users worry about any ExecutionEngineExceptions they might get. (This exception will happily escape any catch block.) No way.
  • Disable mixins for this scenario (generic methods of generic interfaces)
  • Not support languages that depend on custom modifiers, like C++/CLI and, according to Ayende, also F# and Spec#
  • Disable custom modifiers by default, so that users of those languages will have to actively enable it in the configuration, and also take full responsibility for making sure they’re using a .NET release that will not crash.

We’re very likely to go for the last option. We might do that in the Castle project, where Fabian is a commiter (the code that actually triggers this bug is in a DynamicProxy method we’re using), someone else might do it before us, or we could re-implement that DynamicProxy method in our own code, if no agreement can be found among Castle developers.

Opinions are welcome.

SP1 serialization bug

Here’s another connect bug: Be careful with static members of ISerializable types. (Be sure to read Höcke’s comment on the validation page, this seems to be worse than it appeared)

This only broke some unit test, and we were able to work around it. Still, I find it remarkable that a Service Pack would introduce two regression bugs that break our code. Then again, we’re doing some weird stuff, especially in the mixin part, and Fabian really went out of his way to make sure he gets unit test coverage for a wide range of usage scenarios.

(Like, we crashed Mono at Lang.NET with a unit test that tested whether deliberately broken user code would trigger the correct CLR Exception. But I guess it’s part of the magic of an event like that when Marek Safar (the Mono C# guy) analyzes this “bug”, Seo Sanghyeon fixes it within minutes, and Miguel de Icaza triages it for backporting to the Mono release that was branched off the day before. Cool stuff.)

We’ve already discovered quite a few bugs in the past, many of them really low level CLR stuff. (We once even reported a security vulnerability in the CLR, I’ll have to go check what happened to that one. No credits yet.)

But discovering bugs during implementation is one thing. The ratio of bugs that get fixed for the next release is quite OK. Discovering regressions is another story, this breaks code that already worked, or is being used in production, and the ripple effects of such bugs, especially in the CLR itself, can be quite horrible.

All this makes me wonder if Microsoft should not want to include our test suite in their build process. Hell, we’d even give it away without source code so they don’t get blinded by LGPL’ed code! 😉

– Stefan

Written by Stefan Wenig

August 14th, 2008 at 9:09 am

Posted in,mixins

Lang.NET talk video available

with 5 comments

Hi there as well! I’m Fabian Schmied, also from rubicon.

Today, Microsoft has published the video of the talk Stefan and I gave at the Lang.NET symposium 2008, you can find it here (wmv). In the talk, Stefan explains our original motivation for creating re:motion mixins, our mixin library. I give a technical overview about the library (including a very short demo).

This is just the first post providing some insight about re:motion (especially re:motion mixins), though only indirectly. We’ll give more details, explanations, and samples in the near future. In the meantime, feel free to ask specific questions by posting comments to this blog.

– Fabian

Update 2009-03-23: Updated links to the Lang.NET video.

Written by Fabian

February 20th, 2008 at 1:14 pm

Posted in,mixins

Announcing re:motion mixins at 2008

with 3 comments

Hi there, I’m Stefan Wenig, from rubicon informations­technologie in Vienna, Austria. My coworker Fabian Schmied and I just arrived in Redmond for 2008. We’ll be introducing a new mixin mechanism for C# on Tuesday, and we’re going to provide some coverage of mixins here. If time allows, we might also blog a bit about other interesting stuff from, of which there should be plenty.

re:motion is a framework for .NET enterprise applications that we’ve been developing at rubicon for some years now. The mixin mechanism is just one of the libraries it contains, and we’re in the process of moving it all to a OSS development model. If that sounds interesting to you (it should, I promise!), you’ll soon find more information on this blog and on the home page.

This has to be enough for now. Our attendence at has been on pretty short notice, we left Vienna 22 hrs ago. I’m going to sleep, and tomorrow we’ll have to, guess what, finish our presentation.

The next week will see more blogging about re:motion.

– Stefan

Written by Stefan Wenig

January 28th, 2008 at 8:16 am

Posted in,mixins