C++ How do I inherit from a template class, to a template class, with the same arguments

This question already has an answer here except for the fact that I read said question and still couldn't figure out what was wrong.

I am trying to do this:

template<typename T>
class base
{

protected:

    base() {}

    virtual ~base() {}

    virtual void method(void* const voidp) const = 0;

};

template<typename T>
class child : public base<T> // ERROR: child is not a template type
{

public:

    child(std::vector<T> arg)
        : _arg{arg}
    {
    }

    virtual ~child() {}

    void method(void* const voidp) const
    {
        for(template std::vector<T>::const_iterator it = _arg.begin(); it != _arg.end(); ++ it)
        {
            method2(voidp, *it);
        }
    }

protected:

    std::vector<T> _arg;

};

I am slightly confused since this appears to be identical to the linked example, unless I am mistaken?

Edit: This is method2

void method2(void* const voidp, const double& arg) // second argument comes in both double and float formats
{
}

// so there is also a: void method2(void* const voidp, const float& arg)