Simple stream redirection and listener try

main.cpp

#include <iostream>
#include <sstream>
#include <streambuf>
#include <string>

class OStringStreamListener
{
  public:
    virtual void consume(const std::string &input) = 0;
};

class OStringStreamWithEmitter : public std::ostringstream
{
  public:
    OStringStreamWithEmitter(OStringStreamListener &listener) : _listener(listener){};
    std::ostream &operator<<(const std::string &input);

  private:
    OStringStreamListener &_listener;
};

std::ostream &OStringStreamWithEmitter::operator<<(const std::string &input)
{
    _listener.consume(input);

    std::ostringstream << input << std::endl;
    return *this;
}

class SampleOStringStreamListener : public OStringStreamListener
{
  public:
    SampleOStringStreamListener(){};
    ~SampleOStringStreamListener(){};

    std::streambuf *rdbuf() const
    {
        return rdbuf();
    }

    std::string getAll() const;
    void consume(const std::string &input);

  private:
    std::string _customBuffer;
};

void SampleOStringStreamListener::consume(const std::string &input)
{
    _customBuffer += input;
}

std::string SampleOStringStreamListener::getAll() const
{
    return _customBuffer;
}

int main()
{
    using namespace std;

    SampleOStringStreamListener stringStreamListener;
    OStringStreamWithEmitter coutRedirected(stringStreamListener);

    streambuf *coutBackup = cout.rdbuf(coutRedirected.rdbuf());

    cout << "Hello !" << endl;
    cout << "How are you ?" << endl;

    cout.rdbuf(coutBackup);
    cout << "------Got----------" << endl;
    cout << stringStreamListener.getAll() << endl;

    return 0;
}