Pegs vs Triads
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Why the Peggle mobile experience beats GTA
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Beware of using stack-based COM objects from .NET
There are all sorts of nasty things to be aware of if you’re mixing reference-counted COM objects with garbage-collected .NET. For instance, if you’re implementing COM objects in C++ then you’re free to allocate them anywhere you like; on the heap or perhaps on the stack if you know they’re only used in some specific scope.
But what happens if during the lifetime of that stack based COM object, it gets used from .NET? A runtime callable wrapper (RCW) will be created around the object. And this RCW expects to be able to keep the underlying object alive by incrementing its reference count. Of course, the stack-based object will soon go out of scope, and regardless of its reference count the object will be destroyed and the pointer that the RCW contains will no longer be valid. It points into the stack, so when the RCW gets cleaned-up, the CLR will call via this pointer into memory that contains garbage and you’ll get something nasty like an access violation or illegal instruction exception.
A WPF custom control in F#
In the world of WPF with its powerful templating support, you’re much less likely to need to build a custom control from scratch than you are with legacy Windows GUI frameworks. For the vast majority of scenarios it’s possible to take an existing control and modify its appearance and behaviour to get what you need. However it is still possible and sometimes necessary to build something in code. The other day I was looking at creating one – using F# of course – and realised that a skeleton control serves as a good example of the kind of cross-paradigm features the language offers. They’re the kind of things that make it possible to use functional F# with inherently imperative .NET languages and frameworks like WPF.
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Posted in .NET, F#, Software Development, WPF, Windows Tagged .NET, F#, guidattribute fsharp, wpf 2 Comments
Don’t do anything in DllMain… Please
Novice Windows programmers can often think that DllMain is a good place to get that one-time set-up and tear-down work done. It seems to offer an ideal opportunity to know when your DLL has just been loaded, and when it’s about to be unloaded. What better place to add all that expensive, complicated initialisation…? STOP! WAIT! Before you add anything in DllMain, make sure you understand what state the process will be in when it gets called. Once you know that, you may well change your mind…
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Posted in Debugging, Software Development, Uncategorized, Windows Tagged c++, COM, Debugging, dll, win32 Leave a comment
Programming is like a bad analogy
The joy of programming
A quick google reveals some of the funny, interesting and downright weird things that people have compared programming to. Let’s take a closer look at some of them…
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Pinned DataTips in Visual Studio 2010 Beta 2
I’ve just noticed a nice little feature in Visual Studio 2010 Beta 2: pinned DataTips. Values displayed in the debugger as you hover over a variable can now be pinned in place and remain aligned with the source. They can even have annotations added… Tasty!
Comparing lambdas in C++ and F#
The other day someone pointed me to the new MSDN article on C++ lambdas in Visual Studio 2010. Interesting. C++0x has been a long time coming, but in my opinion anything that makes C++ usable at a higher level of abstraction is a good thing. There’s nothing wrong with a little abstraction, as long as you can get to the fundamentals if you need to. Otherwise you wouldn’t be using C++, would you?
But one of the things I couldn’t get over from that article is the verbosity. I’ve just got too used to the succintness of F#. I know this is only example code, so it’s intended to demonstrate usage, but the whole point of lambdas is to reduce boilerplate and make the intent of your code more obvious. So, let’s compare the C++0x implementation with the F# version.
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FormatException in WPF DataBinding
While working on some F#/C# WPF code the other day, I kept hitting a fatal FormatException when running under the debugger. Annoyingly, the app would quit with:
An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll
Additional information: Input string was not in a correct format.
But it worked fine when started from Expression Blend, or when run using Start Without Debugging in Visual Studio. Let’s take a closer look…
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Posted in .NET, Uncategorized, Visual Studio, Windows Tagged .NET, DataBinding, FormatException, visualstudio, wpf Leave a comment
TwitterVision: How Twitter transformed TV
For a long time now, TV executives have bemoaned the lack of “event TV”. Modern broadcast television is a fractured ghost of its previous self. People’s attention is no longer focused in a tight beam on 3 channels; we have millions of videos at a click on YouTube, full-length TV shows and films on iTunes, hundreds of channels on satellite and cable. That means there’s no longer a significant section of society sharing the experience of a television show and discussing it the next day at school/the office water-cooler.
But what they seem to have missed is that something very different, but equally significant, has replaced it: the instantaneously-shared TV experience, enabled by Twitter. With the omnipresence of laptops, broadband and Twitter, the sofa’s now connected. It’s possible to sit at home on your own and discuss, berate and dissect whatever’s on RIGHT NOW.
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