What is the syntax to declare a unique_Ptr variable in a header, then assign it later in the constructor?

Question

I have coded the following, and am very new to c++, and it feels clumsy. I am trying to give 'spriteBatch' (a unique_Ptr) class scope. Here's the header file:

    ref class CubeRenderer : public Direct3DBase
{
public:
    CubeRenderer();
    ~CubeRenderer();


private:

    std::unique_ptr<SpriteBatch> spriteBatch;

};

Then in the cpp file Constructor, this:

std::unique_ptr<SpriteBatch> sb(new SpriteBatch(m_d3dContext.Get()));
spriteBatch = std::move(sb);

It just seems clumsy the way I had to create 'sb' and move it to 'spriteBatch'. attempting to assign directly to 'spriteBatch' failed (maybe I simply don't know the proper syntax). Is there a way to avoid needing to use 'sb' & std::move?

Thank you.

Answer 1

The following should work fine:

spriteBatch = std::unique_ptr<SpriteBatch>(new SpriteBatch(m_d3dContext.Get()));

Alternatively, you can avoid repeating the type name with some make_unique function.

spriteBatch = make_unique<SpriteBatch>(m_d3dContext.Get());

There's also the reset member:

spriteBatch.reset(new SpriteBatch(m_d3dContext.Get()));

But, since you mention a constructor, why not just use the member initialization list?

CubeRenderer::CubeRenderer()
: spriteBatch(new SpriteBatch(m_d3dContext.Get())) {}