The base class : jackport.h
[code]
class JackPortPrivate;
class JackPort
{

public:
JackPort(const QString &name, JackPortFlags type);
virtual ~JackPort();

protected:
virtual void setData(void *data, quint32 nFrames) = 0;
// this function is called by the jack thread
// Implement it to implement your own port
// param: data the buffer that jack provide. It is valid until the function returns
// param: nFrames the number of frames in data
//
JackPortPrivate *const d_ptr;
JackPort(JackPortPrivate &dd);

private:
friend class QJackClient;
friend class QJackClientPrivate;
Q_DECLARE_PRIVATE(JackPort)
};
[/code]

The derived class is:
[code]
#include "jackport.h"

namespace QJack
{
class JackInPort : public JackPort
{
// Inherit from this class if you want to create your own inport

public:
JackInPort(QString &name);
};
} // namespace
[/code]

used as : in_port = new QJack::JackInPort("inport", client->nFrames() * 2, client); (supplied code is not complete)

Some of the background for this is in the KDE-technical article on Binary Compatibility Future Strategies found here: http://techbase.kde.org/Policies/Library_Code_Policy and here: http://techbase.kde.org/Policies/Binary_Compatibility_Issues_With_C++.

What am I missing?