Question

Is it possible to inherit a specialized struct/class like following?

template<class TKey, class TData>
struct Container
{
    virtual void Add(TKey key, TData data) = 0;
};

template<class TData>
struct Container<int, TData>
{
    virtual void Add(int key, TData data) = 0;
};

struct TicketContainer : public Container<std::string>
{
    void Add(int key, std::string data)
    {
    }
};

I am getting errors in TicketContainer declaration complaining too few template parameters declared.

Answer 1

Change:

struct TicketContainer : public Container<std::string>

to:

struct TicketContainer : public Container<int, std::string>

or some other type for TKey.

Even though you have provided a partial specialization of Container you still need to specify both of the template parameters.

You can specify default types for template parameters if you do not want to specify both template parameters. In this case, you would have to reorder TKey and TValue (which may be counter intuitive as associative containers are normally declared key then value):

// Reordered 'TData' and 'TKey'.
template<class TData, class TKey = int>
struct Container
{
    virtual void Add(TKey key, TData data) = 0;
};

template<class TData>
struct Container<TData> // Equivalent to 'struct Container<TData, int>'
{
    // This specialization seems pointless as it defines no
    // special behaviour.
    virtual void Add(int key, TData data) = 0;
};

struct TicketContainer : public Container<std::string>
{
};