Lorien,

This is something I need to add to the documentation. Whenever you write a
callback class FooCallback for a wrapped class Foo, you may need to be sure
that the callback class has a constructor taking 2 arguments, the first
being a PyObject*, the second being a Foo. This constructor is essentially
the to_python copy constructor for Foo, and will be used any time you wrap
a function which returns a Foo by value or by const reference. You only need
to supply this constructor if you wrap such a function, though.

-Dave

----- Original Message -----
From: Lorien Dunn <l.dunn@[...]..> 
To: <boost@[...].com> 
Sent: Thursday, February 08, 2001 10:18 PM
Subject: [boost] BPL : problems with constructors?


>  Hullo,
> 
>  I'm getting some errors I cant make sense of. They are happening in a set
of
>  inter-object Midi reception and transmission classes. These are the only
>  classes affected out of about 75. Attached is a file containing the class
>  interfaces concerned, and the compiler errors.
> 
>  I'm using Mandrake7.2 gcc 2.95.3 (prerelease 1991030) - the default
>  compiler.
> 
>  Thanks for any help :)
> 
>  Lorien Dunn
>  http://members.tripod.com/~loriend
> 
>  ____________________________________________________________________
>  Get free email and a permanent address at http://www.netaddress.com/?N=1
> 
> 
> 


----------------------------------------------------------------------------
----


> 
////////////////////////////////////////////////////////////////////////////
/////////////////////
>  // Reciever classes
> 
////////////////////////////////////////////////////////////////////////////
/////////////////////
> 
>  class Transmitter;
> 
>  class RecieverPyCallback : public Reciever
>  {
>  PyObject* _self;
>  public:
>  RecieverPyCallback(PyObject* self);
>  virtual ~RecieverPyCallback();
> 
>  virtual void Parse(const Event& ev);
>  static void DefaultParse(Reciever& self, const Event& ev);
> 
>  virtual void OnEvent(const Event& ev);
>  static void DefaultOnEvent(Reciever& self, const Event& ev);
> 
>  //Connection callbacks
>  virtual void ConnectionMade(Transmitter& from);
>  static void DefaultConnectionMade(Reciever& self, Transmitter& from);
> 
>  virtual void ConnectionBroken(Transmitter& from);
>  static void DefaultConnectionBroken(Reciever& self, Transmitter& from);
>  };
> 
>  struct PyReciever : python::class_builder<Reciever,RecieverPyCallback>
>  {
>  PyReciever(python::module_builder& m) :
>  python::class_builder<Reciever,RecieverPyCallback>(m, Reciever )
>  {
>  def(python::constructor<>());
>  def(&Reciever::Parse, Parse ,&RecieverPyCallback::DefaultParse);
>  def(&Reciever::OnEvent, OnEvent ,&RecieverPyCallback::DefaultOnEvent);
> 
def(&Reciever::ConnectionMade, ConnectionMade ,&RecieverPyCallback::DefaultC
onnectionMade);
> 
def(&Reciever::ConnectionBroken, ConnectionBroken ,&RecieverPyCallback::Defa
ultConnectionBroken);
>  def(&Reciever::Parse, Parse ,&RecieverPyCallback::DefaultParse);
>  def(&Reciever::OnEvent, OnEvent ,&RecieverPyCallback::DefaultOnEvent);
>  };
>  virtual ~PyReciever() throw() {};
>  };
> 
> 
////////////////////////////////////////////////////////////////////////////
/////////////////////////
>  // Transmitter classes
> 
////////////////////////////////////////////////////////////////////////////
//////////////////////////
> 
> 
>  class TransmitterPyCallback : public Transmitter
>  {
>  PyObject* _self;
>  public:
>  TransmitterPyCallback(PyObject* self);
>  virtual ~TransmitterPyCallback();
> 
>  virtual void Connect(Reciever& dest);
>  static void DefaultConnect(Transmitter& self, Reciever& dest);
> 
>  virtual void Disconnect(Reciever& dest);
>  static void DefaultDisconnect(Transmitter& self, Reciever& dest);
> 
>  virtual void Emit(const Event& ev));
>  static void DefaultEmit(Transmitter& self, const Event& ev);
> 
>  virtual void ConnectionBroken(Reciever& dest);
>  static void DefaultConnectionBroken(Transmitter& self, Reciever& dest);
>  };
> 
>  struct PyTransmitter : python::class_builder<Transmitter,
TransmitterPyCallback> 
>  {
>  PyTransmitter(python::module_builder& m) :
>  python::class_builder<Transmitter, TransmitterPyCallback>(m,
Transmitter )
>  {
>  def(python::constructor<>());
>  def(&Transmitter::Emit, Emit ,&TransmitterPyCallback::DefaultEmit);
>  def(&Transmitter::Connect, Connect ,
&TransmitterPyCallback::DefaultConnect);
>  def(&Transmitter::Disconnect, Disconnect ,
&TransmitterPyCallback::DefaultDisconnect);
> 
def(&Transmitter::ConnectionBroken, ConnectionBroken ,&TransmitterPyCallback
::DefaultConnectionBroken);
>  };
>  virtual ~PyTransmitter() throw() {};
>  };
> 
> 
////////////////////////////////////////////////////////////////////////////
/////////////////////////////////
>  // Error Messages
> 
////////////////////////////////////////////////////////////////////////////
//////////////////////////////////
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp: In method
`boost::python::detail::instance_value_holder<Burt::Midi::Transmitter,Burt::
Midi::TransmitterPyCallback> ::instance_value_holder<Burt::Midi::Transmitter>
(boost::python::detail::extension_instance *, Burt::Midi::Transmitter)':
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp:178:
instantiated from
`python_extension_class_converters<Burt::Midi::Transmitter,Burt::Midi::Trans
mitterPyCallback> ::to_python(const Burt::Midi::Transmitter &) const'
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp:299:
instantiated from `to_python<Burt::Midi::Transmitter> (const
Burt::Midi::Transmitter &)'
> 
>  /home/lorien/boost/boost/python/callback.hpp:458: instantiated from here
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp:680: no
matching function for call to
`Burt::Midi::TransmitterPyCallback::TransmitterPyCallback
(boost::python::detail::extension_instance *&, Burt::Midi::Transmitter &)'
> 
>  PyMidi/PySignals.cpp:349: candidates are:
Burt::Midi::TransmitterPyCallback::TransmitterPyCallback(PyObject *)
> 
>  PyMidi/PySignals.h:294:
Burt::Midi::TransmitterPyCallback::TransmitterPyCallback(const
Burt::Midi::TransmitterPyCallback &)
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp: In method
`boost::python::detail::instance_value_holder<Burt::Midi::Reciever,Burt::Mid
i::RecieverPyCallback> ::instance_value_holder<Burt::Midi::Reciever>(boost::p
ython::detail::extension_instance *, Burt::Midi::Reciever)':
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp:178:
instantiated from
`python_extension_class_converters<Burt::Midi::Reciever,Burt::Midi::Reciever
PyCallback> ::to_python(const Burt::Midi::Reciever &) const'
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp:299:
instantiated from `to_python<Burt::Midi::Reciever> (const
Burt::Midi::Reciever &)'
> 
>  /home/lorien/boost/boost/python/callback.hpp:458: instantiated from here
> 
>  /home/lorien/boost/boost/python/detail/extension_class.hpp:680: no
matching function for call to
`Burt::Midi::RecieverPyCallback::RecieverPyCallback
(boost::python::detail::extension_instance *&, Burt::Midi::Reciever &)'
> 
>  PyMidi/PySignals.cpp:6: candidates are:
Burt::Midi::RecieverPyCallback::RecieverPyCallback(PyObject *)
> 
>  PyMidi/PySignals.h:86:
Burt::Midi::RecieverPyCallback::RecieverPyCallback(const
Burt::Midi::RecieverPyCallback &)
> 
> 
////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////
>  // EOF
> 
////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////
>