How to Marshall C++ Native Objects to Managed C++ CLI

Question

Hello,

I have bunch of native C++ objects and classes contains DTL maps, maps of maps and lists and vectors.

I need to call managed C++ functions from C++ native code and need to pass these native objects and STL containers(lists,maps , maps of maps) to C++/CLI. It needs to marshal or some how serialize these objects. How can I do that with out any problem. So that After marshalling and serializing back to managed C++/CLI , maps should marshalled with dictionaries and dictionaries of dictionaries, stl list with managed List<> and so on..

how can I achieve this for all cases? Is it requires complex handling of marshalling issues...?

Regards Usman

Answer 1

STL memory layout is implementation specific. E.g. sizeof(std::vector) is 16 in release and 20 in debug mode when you use the implementation comes with Visual C++. And you have pointers in STL classes that can't be marshaled meaningfully to managed memory. You can switch to platform-independent C or COM types in the interface (e.g. pass an array with a count parameter or a safe array) if you want to do marshaling as .Net has better understanding on these types. I recommend COM because it has richer types and support other languages in case you need it.

Alternatively if you need speed you can write a marshal_as template function to do the conversion so you can reuse the marshaling code or even the marshaling buffer, or write a managed wrapper for your C++ objects.

If the data being marshaled is too large to fit in the memory you can also serialize the data to temp file or database and read them back from managed code in chunks.