In my last job interview I got a (rather vague) question about traversing a tree and operating on the tree nodes. I think I’ve a lot of experience in programming but I couldn’t figure out the answer on my own. The answer the guy wanted to hear was: visitor pattern.

I had never heard of it before. So, in preparation for my next job interview, I thought I take a look at it.

While trying to figure it out, I stumbled over this quote:

The Visitor pattern is possibly the most complicated design pattern you will face. (Source)

I totally agree. (And this is probably why I’ve never heard or used it before.)

But since I’m not a quitter I went on and tamed it. So, in this article I’m going to shed some light on this mysterious design pattern.

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P/Invoke tries to make your life easier by automatically converting (“marshalling”) data types from managed code to native code and the other way around.

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Sometimes a C/C++ function needs to store data you pass to it for later reference. If such data is a managed object (like a string or class) you need to make sure that the garbage collector doesn’t delete it while it’s still used/stored in the native code.

That’s what pinning is for. It prevents the garbage collector from deleting and moving the object.

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Security is hard. In a current project I saw some code that created some access tokens based on a random number generator – .NET’s Random class. The code used an instance of Random stored in static field and I got curious:

If you have such a long living Random instance, could you predict the random values after generating a few of them?

It turns out, it is possible. And you only need to read 56 55 “random” values to predict all future values.

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Recently, I wanted to try out the new .NET Core together with a Docker container. However, coming from programing .NET applications for the regular .NET Framework, there were some obstacles I encountered. This one is about NuGet packages.

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