About abstract classes inheritance

[DBarzo]

Hi,

I have a little problem with a tree of abstract classes.
My interfaces definitions are:

struct IAudioDevice
{
  virtual void IAudioDeviceMethod() = 0;
}

//----------------------------------------------------------------

struct IAudioRecorder : virtual public IAudioDevice
{
  virtual void IAudioRecorderMethod() = 0;
}

//----------------------------------------------------------------

struct ICodec
{
  virtual void ICodecMethod() = 0;   
};

//----------------------------------------------------------------

struct IAudioDecoder : public ICodec, public virtual IAudioRecorder
{
  virtual void IAudioDecoderMethod() = 0;
};

//----------------------------------------------------------------

struct IAudioInputRepeater : public IAudioDecoder
{
  virtual void IAudioInputRepeaterMethod() = 0;
};

and the implementation is:

class AudioDevice : virtual public IAudioDevice
{
public:
  void IAudioDeviceMethod() { /* IMPLEMENTATION */ };
};

//----------------------------------------------------------------

class AudioRecorder : public IAudioRecorder,
                      public AudioDevice
{
public:
  void IAudioRecorderMethod() { /* IMPLEMENTATION */ };
};

//----------------------------------------------------------------

class AudioDecoder : public AudioRecorder,
                     public IAudioDecoder
{
public:
  virtual void IAudioDecoderMethod() { /* IMPLEMENTATION */ };
  virtual void ICodecMethod() { /* IMPLEMENTATION */ };
};

//----------------------------------------------------------------

class AudioInputRepeater : public IAudioInputRepeater,
                           public AudioDecoder
{
public:
  void IAudioInputRepeaterMethod() { /* IMPLEMENTATION */ };
};

When I try to instantiate an AudioInputRepeater object the compiler raise the error:

"cannot instantiate abstract class due to following members:"

ICodec::ICodecMethod()
IAudioDecoder::IAudioDecoderMethod()

Why this happen?
This class is derived from the concrete class AudioDecoder which defines these methods!

Regards,
Daniele.

[DBarzo]

Ok,

I answer to myself! :-)
I simply forgot a "virtual" keyword:

struct IAudioDecoder : public virtual ICodec, public virtual IAudioRecorder
{
  virtual void IAudioDecoderMethod() = 0;
};

Daniele.