Dev102's Challenge 12:Managed & unmanaged

My solution(s) for last week’s challenge were cited, but, only as an “honorable mention” / “also run”.

This week’s challenge is a different sort of animal. Not that it is particularly difficult — actually I suspect it’s quite easy — it’s just that it requires a fairly specialize knowledge (Managed Extensions for C++ in this case). A couple of them in the past required some basic knowledge of .Net & the CLR, but most of the time, the challenge involve a non-platform specific algorithm.

So, knowing nothing about Managed Extensions, I was just going to let this one pass. But, I happened to run into an old friend (Will Depalo) from my days as a VC++ MVP. When I went to .Net, I also switched to C#, but he stayed with C++, so I figured he would have some insight. Reducing the problem to one sentence (“we have a unmanaged class accessing an instance variable of a managed class”), and he immediately knew the answer (“you’ll need to pin it”), and offered some advice (“look up __pin in the MSDN”). However, didn’t realize exactly how good that advice was, as the folk’s at DEV102 apparently took the example source code from the __pin article to create the challenge. So, here’s my answer (I love stuff that can be answer via copy’n’paste):

int main() 
{
   ManagedClass __pin * pMngdClass = new ManagedClass;
   UnmanagedClass* pUnmngd = new UnmanagedClass;
   pUnmngd->incr(&(pMngdClass->i));
}

The rest is unchanged.