Question

How’s that for a catchy title?

I need to convert back and forth from a CLR compliant type, like an array, and a std::vector type.

Are there any adapter methods out there, or should I just keep copying it in and out each time I call one of my native methods?

There are some interesting methods for converting between the cliext STL variant classes and CLR types, but I’m at a loss for how to get the standard vector into the STL types without a for next loop.

This is what I’m doing all over the place in this project:

vector<double> galilVector = _galilClass->arrayUpload(marshal_as<string>(arrayName));
List<double>^ arrayList = gcnew List<double>();

// Copy out the vector into a list for export to .net
for(vector<double>::size_type i = 0; i < galilVector.size(); i++) 
{
    arrayList->Add(galilVector[i]);
}

return arrayList->ToArray();

Answer 1

Instead of “doing that all over the place”, why don’t you make that logic into a reusable function?

Something like

template<typename T>
generic<typename S>
std::vector<T> marshal_as(System::Collections::Generic::ICollection<S>^ list)
{
  if (list == nullptr) throw gcnew ArgumentNullException(L"list");
  std::vector<T> result;
  result.reserve(list->Count);
  for each (S& elem in list)
    result.push_back(marshal_as<T>(elem));
  return result;
}

Remember to use vector’s swap member function to quickly move the elements into the vector you want to hold them, if you just assign then a zillion copy constructors would be called.