C / C++ / MFC

T::UnitList Units;

typename T::UnitList Units;

template <class T>
class Measure
{
public:
   double Value;
   typename T::UnitList Units;

   virtual const T& Convert(const typename T::UnitList destUnits) = 0;
    // Declare a number of other pure virtual functions
};

// Length Declaration in "Length.h"
class Length : public Measure<Length>
{
public:
   enum UnitList
   {
      METERS,
      MILES,
   };
   virtual const Length& Convert(const UnitList destUnits)
   {

   }
};

b.cpp: In instantiation of ‘Measure<Length>’:
b.cpp:12:   instantiated from here
b.cpp:5: error: invalid use of undefined type ‘class Length’
b.cpp:12: error: forward declaration of ‘class Length’
b.cpp:7: error: invalid use of undefined type ‘class Length’
b.cpp:12: error: forward declaration of ‘class Length’

template <class T>
class Measure
{
public:
   double Value;

   virtual const T& Convert(const int destUnits)
   {
      static_cast<T*>(this)->Flip();
   }
    // Declare a number of other pure virtual functions
};

// Length Declaration in "Length.h"
class Length : public Measure<Length>
{
public:
   enum UnitList
   {
      METERS,
      MILES,
   };
   virtual const Length& Convert(const UnitList destUnits)
   {
      Measure<Length>::Convert(1);
   }
   void Flip() {}
};

// "Measure.h"
template <class Derived, class UnitType>
class Measure {
public:
   double   Value;
   UnitType Units;

   virtual const Derived& Convert(const UnitType destUnits) = 0;

   // Declare a number of other pure virtual functions
};

// "Length Units.h"
class LengthUnits {
public:
    enum List {
        METERS,
        MILES,
    };
};

// "Length.h"
class Length : public Measure<Length, LengthUnits> {
public:
   // Declare additional methods
};

RichardBrock wrote:

Weird.

led mike wrote:

What are you compiling to?

LOGFONT logFont;
my_control.GetFont()->GetLogFont(&logFont);
_tcscpy(logFont.lfFaceName, _T("the_name_of_my_favourite_font"));
my_controls_font.CreateFontIndirect(&logFont);
my_control.SetFont(&my_controls_font);