Use C# properties in unmanaged C++ code

Question

We have a large project mainly written in C# (services, multithreading etc.). However, the core number crunching algorithms are written in unmanaged C++ to be fast (OpenMP etc.).

Unfortunately, at the moment we have to do a lot of effort to exchange data between these two worlds. I.e., we have to write wrapping classes in C++/CLI for each of the C++ classes. For (virtually) any required setting (Properties) in the C#-"world" there is a copy in the C++ world (a header file) and an explicit conversion back and forth in the wrapper class. This architecture seems very inefficient and quite error-prone.

Primary question: Is there a way to share a C#-class with properties somehow automatically in unmanaged C++? (we have to read and write!)

Secondary question: Could you give any advice of how to improve the architecture in a case as described above. One consideration of ours was to completely switch to C++, but having to find appropriate libraries and write clean code for all the (system-)things we do in .NET at the moment does not feel good.

Many thanks for your help and best regards, Jakob

Answer 1

I am dealing with similar issues at my work where my primary task is to write managed interfaces to certain high perfromance, low latency dlls, this involves simple cases where I have to wrap the native classes using simple c++/cli containing a raw pointer to the native class or more complex issues where the native code is a server side publisher and the managed code has to subscribe to it using delegates ie they have to be converted to native callbacks. .NET under the hood is a sophisticated COM server as far as I know. It is possible to write .net assemblies with the ComVisible attribute set to true then it acts as a classic COM component and then it is possible to use it from the native C++ code as a COM component. The reverse that is to use native code from managed can be achieved using the DllImport attributes and all the Marshaling can be fine tuned by the various attributes like the StructLayoutAttribute (http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.structlayoutattribute.aspx) and the MarshalAsAttribute (http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.marshalasattribute.aspx) I am also using sometimes the unsafe keyword as well. I have to deal with high performance code so in some cases it is that after profiling that I know which is the best solution. Whether it is the warpper class solution that you have mentioned or the classic COM way, or some kind of hybrid with some caching, object pooling etc.

Hope that helps. :)

Apologies if that looks a bit disorganised. It is very late here. :)