C++ varadic arguments - function will not take in any additional arguments

Question

I am working with varadic arguments to try to template a class I am using, and I get an error that the function does not take 3 arguments when I try to call the addComponent function in my class. I am very unsure as to why this is, and I haven't found a fix yet.

Class Code:

template <typename T, typename... Args>
class RenderComponentGroup : public RenderGroupBase
{
public:
using RenderGroupBase::RenderGroupBase;
void iterate() { IterateRenderComps<T>(m_Components); };
void addComponent(std::vector<RenderComponent*>* compPointers, Args... arguments)
{
    //Check if any dead
    for (int i = 0; i < m_Components.size(); i++)
    {
        if (m_Components[i].isDead())
        {
            m_Components.emplace(m_Components.begin() + i, arguments...);
            m_Components[i].updatePointer();
            return;
        }
    }

    //Resize components array
    m_Components.emplace_back(arguments...);
    m_Components[m_Components.size() - 1].attachToObject(compPointers);
    for (int i = 0; i < m_Components.size(); i++)
    {
        m_Components[i].updatePointer();
    }
}
private:
    unsigned int m_ID = 0;
    std::vector<T> m_Components;
};

Function called:

std::shared_ptr<RenderComponentGroup<SpriteRender>> spriteGroup(new   RenderComponentGroup<SpriteRender>());
//Everything after renderComps is the arguments
spriteGroup->addComponent(&sprite->m_RenderComps, &sprite->m_Sprite, &m_SpriteRenderer);

Error:

Error   C2660   'RenderComponentGroup<SpriteRender>::addComponent': function does not take 3       arguments    SpaceEngine D:\Repositories\Space Engine\SpaceGame\src\game\states\Overworld.cpp    33  

Answer 1

I found the error just after I posted this, and I feel very stupid.

The arguments were declared at the top of the class, which meant that on creation the args resolved to be empty. Because this is technically valid, it didn't throw an error until I tried to add arguments to the function. Moving template<typname... Args> to the top of the function itself means that it resolves to the arguments in the function call.

Fixed:

template <typename T>
class RenderComponentGroup : public RenderGroupBase
{
public:
template<typename... Args>
void addComponent(std::vector<RenderComponent*>* compPointers, Args... arguments)
{
    //Check if any dead
    for (int i = 0; i < m_Components.size(); i++)
    {
        if (m_Components[i].isDead())
        {
            m_Components.emplace(m_Components.begin() + i, arguments...);
            m_Components[i].updatePointer();
            return;
        }
    }

    //Resize components array
    m_Components.emplace_back(arguments...);
    m_Components[m_Components.size() - 1].attachToObject(compPointers);
    for (int i = 0; i < m_Components.size(); i++)
    {
        m_Components[i].updatePointer();
    }
}
private:
    unsigned int m_ID = 0;
    std::vector<T> m_Components;
};