Don't return the whole array of class member variable.

For example,

class Skeleton
{
    // recommended
    BodyNode* getBodyNode(int i) const;
    int getNumBodyNodes() const
    
    // not recommended
    // const std::vector<BodyNode*>& getBodyNodes() const;

protected:
    std::vector<BodyNode*> mBodyNodes;
    // ...
};