class SequencePrinter
{
public:
    // ...
    virtual void print() const = 0;
    virtual void setSequence(const SequenceGenerator & sequence) = 0;

    void changeSequence(const SequenceGenerator & sequence)
    {
        this->m_sequence = sequence;
    }

private:
    SequenceGenerator & m_sequence;
};

class SequencePrinterToString : public SequencePrinter
{
public:
    // ...
    void print() const { /*imlementation of print*/ }

    void setSequence(const SequenceGenerator & sequence)
    {
        changeSequence(sequence);
    }
private:
};