VS.NET - non-type template classes with FLOAT

Posted on 2003-11-12
Last Modified: 2010-04-02

I am having a problem compiling one of my projects (VS.NET, project imported from VC6), because there is a problem with how VS.NET handles FLOATS in non-type template classes. I have checked out MSDN : BUT no joy as it says if it is a class template which mine is, there is no easy workaround.

So to my question, does anyone know of a way to solve this ? I am thinking that i will have to write a new class to include the float parameters only, and take them out of the template class. Is this the correct way ? For your info, below is my template class.

template<class T, TypeID_gem_t TypeID, T Invalid>
class CGEM_ArrayItem : public CGEM_DataItem
      LPCSTR      m_pszName;
      T*            m_pVal;
      size_t      m_cElemCount;
      TypeID_gem_t m_type;

       CGEM_ArrayItem(const TGEM_DATA_DEF& DataDef)  
             : m_cElemCount(DataDef.ItemCount),

            m_pVal = new T[m_cElemCount];

            if(m_pVal == 0)
                  m_cElemCount = 0;
                  for(int i = 0; i < m_cElemCount; i++)
                              m_pVal[i] = Invalid;

            m_pszName = ::_strdup(DataDef.pszItemName);

            TGEM_DATA d;
            d.val = DataDef.IniVal;
            d.ParType = DataDef.ParType;


            delete[] m_pVal;

      static SAFEARRAY* GetSafeArray(const TGEM_DATA& data)
                  case GEM_I8_ARRAY:      return data.val.I8_array;
                  case GEM_I16_ARRAY:      return data.val.I16_array;                  
                  case GEM_I32_ARRAY:      return data.val.I32_array;
                  case GEM_I64_ARRAY:      return data.val.I64_array;

                  case GEM_SF_ARRAY:      return data.val.SF_array;      //singlefloat      
                  case GEM_DF_ARRAY:      return data.val.DF_array;      //doublefloat            

                  case GEM_U8_ARRAY:      return data.val.U8_array;                  
                  case GEM_U16_ARRAY:      return data.val.U16_array;                  
                  case GEM_U32_ARRAY:      return data.val.U32_array;                  
                  case GEM_U64_ARRAY:      return data.val.U64_array;                  
                  case GEM_B_ARRAY:      return data.val.B_array;                  

                        return NULL;

      HRESULT Set(const TGEM_DATA& data)
            HRESULT hr = E_INVALIDARG;
            SAFEARRAY *psa = GetSafeArray(data);

            if(psa != NULL)            
                  ULONG size = sizeof T;
                  ATLASSERT(SafeArrayGetElemsize(psa) == sizeof T);
                  void *pSrc;
                  hr = SafeArrayAccessData(psa, &pSrc);

                        long plUbound;

                        hr = SafeArrayGetUBound(psa, 1, &plUbound);

                        if(SUCCEEDED(hr) && ++plUbound == m_cElemCount)
                              memcpy(m_pVal, pSrc, plUbound * sizeof T);
                              hr = E_INVALIDARG;

            return hr;

      TypeID_gem_t      GetType() { return m_type; }
      Data_gem_t*            GetData() { return m_pVal; }
      LPCSTR                  GetName() { return m_pszName; }
      Integer32_gem_t GetElementCount() { return m_cElemCount; }

      void Invalidate()
                  for(int i = 0; i < m_cElemCount; i++)
                        m_pVal[i] = 0;

Any help would be most appreciated in this porting exercise from VS6 to VS.NET C++.

Kind Regards

Question by:upliftin
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LVL 17

Accepted Solution

rstaveley earned 200 total points
ID: 9734842
I think you have to pass it as a constructor parameter :-(

#include <iostream>

template<class T> class TC {
        const T initialiser;
        TC(T initialiser) : initialiser(initialiser) {}
        void print() const { std::cout << "Initialiser is " << initialiser << '\n';}

int main()
        TC<double> tc(123.456);

Expert Comment

ID: 10249035
No comment has been added lately, so it's time to clean up this TA.
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