C++ example

#include <memory>
#include <iostream>
#include <cassert>
#include <vector>
#include <utility>

class ITransport
{
public:
    virtual ~ITransport() = default;
};

using ITransportPtr = std::unique_ptr<ITransport>;

class NetworkTransport : public ITransport
{
public:
    ~NetworkTransport() override = default;
};

class SerialTransport : public ITransport
{
public:
    ~SerialTransport() override = default;
};

class A
{
public:
    A()
    {
        add_transport<NetworkTransport>();
        add_transport<SerialTransport>();
    }

    int transport_count() { return m_transports.size(); }

private:
    template <typename T>
    void add_transport()
    {
        auto tr = std::make_unique<T>();
        m_transports.push_back(std::move(tr));
    }

private:
    std::vector<ITransportPtr> m_transports;
};

int main()
{
    A a;
    std::cout << a.transport_count() << std::endl;
}