vector of unique_ptr in C++11

Question

I recently switched to C++11 and I'm trying to get used to good practices there. What I end up dealing with very often is something like:

class Owner
{
private:
    vector<unique_ptr<HeavyResource>> _vectorOfHeavyResources;
public:
    virtual const vector<const HeavyResource*>* GetVectorOfResources() const;
};

This requires me to do something like adding a _returnableVector and translating the source vectors to be able to return it later on:

_returnableVector = vector<HeavyResource*>;
for (int i=0; i< _vectorOfHeavyResources.size(); i++)
{
    _returnableVector.push_back(_vectorOfHeavyResources[i].get());
}

Has anyone noticed similar problem? What are your thoughts and solutions? Am I getting the whole ownership idea right here?

UPDATE: Heres another thing: What if one class returns a result of some processing as vector<unique_ptr<HeavyResource>> (it passes the ownership of the results to the caller), and it is supposed to be used for some subsequent processing:

vector<unique_ptr<HeavyResource>> partialResult = _processor1.Process();
// translation
auto result = _processor2.Process(translatedPartialResult); // the argument of process is vector<const HeavyResource*>

Answer 1

I would suggest that instead of maintaining and returning an un-unique_ptred vector, you provide functions to access the elements directly. This encapsulates the storage of your resources; clients don't know that they are stored as unique_ptrs, nor that they are kept in a vector.

One possibility for this is to use boost::indirect_iterator to dereference your unique_ptr automatically:

using ResourceIterator =
     boost::indirect_iterator<std::vector<std::unique_ptr<HeavyResource>>::iterator,
                              const HeavyResource>;
ResourceIterator begin() { return std::begin(_vectorOfHeavyResources); }
ResourceIterator end() { return std::end(_vectorOfHeavyResources); }

Demo