My Goal

I am using an OpenCL Wrapper for GPU processing in C++. This library creates memory objects as:

Memory<float>(gpuDevice, sizeOfMemoryObject)

I need to create several lists of these each within a vector<Memory<float>>. It is not important to me whether anything is an object or pointer as long as it is smart, safe, and works. At no point am I intending or wanting to copy the actual objects around.

In simple terms, if it wasn’t for pointers issues (pseudo-code of C++/C#), what I would want to do (in the best words I can express it):

private:

//define the main objects/pointers I will access throughout my code 

std::vector<Memory<float>> memoryVecA;  
std::vector<Memory<float>> memoryVecB;  
std::vector<Memory<float>> memoryVecC;  
... //more, D, E, F, etc.

On initialization, I want to first add these to a temp parent vector. This is to allow iteration through them to initialize them and their contents:

//temporary list to iterate through just for construction
std::vector<std::vector<Memory<float>> tempMemoryVec; 

//add the main objects to it
tempMemoryVec.emplace_back(memoryVecA);
tempMemoryVec.emplace_back(memoryVecB);
tempMemoryVec.emplace_back(memoryVecC);

Then right after that, I want to iterate through this temp list to fill it all in:

int numMemoriesPerVector = 10; // number of Memory<float>'s to add to each memoryVec
int numSamplesPerMemory = 100; // construction parameter for size of each Memory<float> 

for (int i=0; i < tempMemoryVec.size(); i++){

    //fill in memoryVecA/B/C by accessing them from the tempMemoryVec
    for (int j=0; j < numMemoriesPerVector; j++){

        //create the memory objects and add them to memoryVecA/B/C 
        Memory<float> newMemory = Memory<float>(gpuDevice, numSamplesPerMemory);
        tempMemoryVec[i].emplace_back(newMemory); //add Memory<float> to vector<Memory<float>>

        //set all memory values to zero
        for (int k=0; k < numSamplesPerMemory; k++){
            newMemory[k] = 0;
        }
        //copy data to GPU inside Memory<float> object (internal function of it)
        newMemory.write_to_device(); 

    }

}
tempMemoryList.clear(); //no longer need this - was just temporary list to make initialization easier

At the end, I need want my Vector<Memory<float>> memoryVecA etc. (pointers or objects) where each Vector has 10 Memory<float> entries, each of which is then filled with 100 zeros.

I then must access these Vectors and their contained Memory<float> objects easily and routinely from there.

My Failed Attempts

I have spent hours today trying to make this work. I have tried all sorts of pointers, passing things in by reference, make_shared, etc. but it is just getting so complicated with all the nested brackets and asterixes etc. I don’t have the knowledge of how it is working and what I am doing.

I am not sure when I am copying an object or just the pointer, etc. I keep just getting errors and I can’t spend another 2-3 days just failing on something trivial like this. The Memory objects are expensive so I can’t be copying them around unnecessarily and it will break function.

Is there anyone who would be very kind as to help me write some version of what I am trying to do above in a way that doesn’t become overly complicated but allows creation and initialization of the vector<Memory<float>> objects I want (and/or some variant of pointers/objects for these?)

I often want to do something like this but then I struggle. C++ pointers and references have always been difficult for me. I’d appreciate some help. This is a common situation for me, so it would be good to learn from.

Thanks for any help.