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VE7JRO
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dj_segfault
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class Pin
{
  public:
   ...
  protected:
   ...
  // This method is child-specific. It's empty in this base class
  virtual void setPinValue(int value)=0;
};

class Pin
{
  public:
  ....
  // This method is child-specific. It's empty in this base class
  virtual void setPinValue(int value)=0;
};

class Pin
{
  public:
   ...
  protected:
   ...
  // This method is child-specific. It's empty in this base class
  virtual void setPinValue(int value)=0;
};
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dj_segfault
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Inheritance not working as expected

Short version: This is a lighting control project. Some of the clases are Pin and Channel. Channel contains a Pin. Pin is a base class for DigitalOutPin and will be the base class for AnalogOutPin, and I want Channel to be able to use any child of Pin.

Pin has an abstract method setPinValue(), but when I create a DigitalOutPin object and call setPinValue(), Pin.setPinValue() gets called, not DigitalOutPin.setPinValue() and my program doesn't work because Pin.setPinValue() is empty as it's supposed to be overwritten.

Long version: If I leave out the definition of Pin.setPinValue(), I get that most idiotic of error gcc messages, "undefined reference to `vtable for Pin'". If I make it pure virtual I get several errors in the form of

In file included from /devel/arduino/lightbright/LightBrightMain/LightBrightMain.ino:9:0:
/devel/arduino/libraries/LightBrightLib/Channel.h:21:20: error: cannot declare parameter 'pin' to be of abstract type 'Pin'
     void begin(Pin pin, int channelNumber);
                ^
In file included from /devel/arduino/libraries/LightBrightLib/DigitalOutPin.h:10:0,
             from /devel/arduino/lightbright/LightBrightMain/LightBrightMain.ino:8:
/devel/arduino/libraries/LightBrightLib/Pin.h:16:7: note:   because the following virtual functions are pure within 'Pin':
 class Pin
   ^
/devel/arduino/libraries/LightBrightLib/Pin.h:33:18: note:  virtual void Pin::setPinValue(int)
     virtual void setPinValue(int value)=0;
              ^
In file included from /devel/arduino/lightbright/LightBrightMain/LightBrightMain.ino:9:0:
/devel/arduino/libraries/LightBrightLib/Channel.h:23:9: error: invalid abstract return type for member function 'Pin Channel::getPin()'
 Pin getPin();
     ^
In file included from /devel/arduino/libraries/LightBrightLib/DigitalOutPin.h:10:0,
             from /devel/arduino/lightbright/LightBrightMain/LightBrightMain.ino:8:
/devel/arduino/libraries/LightBrightLib/Pin.h:16:7: note:   since type 'Pin' has pure virtual functions
 class Pin
   ^

Full code is at GitHub but here are the relevant parts: Pin is declared like this right now as pure virtual, but I've tried with and without =0

class Pin
{
  public:
  ....
  // This method is child-specific. It's empty in this base class
  virtual void setPinValue(int value)=0;
};

DigitalOutPin is declared as

class DigitalOutPin : public Pin
{
  public:
    void on();
    void off();
  protected:
    void setPinValue(int value);
};

and defined as

void DigitalOutPin::setPinValue(int value) {
....
}

Disclaimer: I'm primarily a Java developer so C++ OO is very different for me, but as far as I can tell this should work as designed.

Thanks for any advice you can offer.