[boost] lambda problem (VC7.0 and GNU Dev-C++)

10 Jan 2005

      Hello All,

Problem is:
what the difference between "type" in such cases?

1)
class type{};

and

2)
class type1{};
typedef type1 type;

I think, they are equal. But... look code.

/////////////////////////////////////
//// Begin of code
/////////////////////////////////////

#include <boost\mpl\apply.hpp>
#include <boost\mpl\lambda.hpp>
#include <boost\mpl\placeholders.hpp>
namespace mpl = boost::mpl;

struct CClass{ void Init(int& i){i--;};};

namespace impl
{
    template<typename TBase> struct CClass0:public TBase {
    public:  void Init(int& i){i--; TBase::Init(i);};
    };
    template<typename TBase> struct CClass1:public TBase {
    public:  void Init(int& i){i--;     TBase::Init(i);}
    ;};
}

typedef mpl::lambda<impl::CClass0<mpl::_> >::type CClass0;
typedef mpl::lambda<impl::CClass1<mpl::_> >::type CClass1;

template <typename T1, typename T2> struct CMetaFunction1
{
        struct type1: public mpl::apply<T1, T2>::type{};
        typedef type1 type;
};

template <typename T1, typename T2> struct CMetaFunction2
{
        struct type: public mpl::apply<T1, T2>::type{};
};

class CBase
{
        CBase(void)
        {
        {
        CMetaFunction1<CClass1, CMetaFunction1<CClass0, CClass>::type >::type g;
        int i=5;
        g.Init(i);
        }

{
        CMetaFunction2<CClass1, CMetaFunction2<CClass0, CClass>::type >::type g;
        int i=5;
        g.Init(i);
        }        
        }
};

///////////////////////////////////////////////
end of code
//////////////////////////////////////////////

Explanation:
Want
    impl::CClass1<impl::CClass0<CClass> >;

    and running g.Init();

        CClass1::Init();
        CClass0::Init();
        CClass::Init();

using CMetaFunction1 everything is OK.
but CMetaFunction2 gives

        CClass0::Init();
        CClass::Init();

WHY ???

Tested on VC++7.0 and GNU Dev-C++

P.S. when use my own lamda function
Both variants works OK.

///////////////////////////////////////////////
template <template <typename> class TBase> struct lambda
{
        template <typename T> struct apply
        {
                typedef TBase<T> type;
        };
};

typedef lambda<impl::CClass0> CClass0;
typedef lambda<impl::CClass1> CClass1;
///////////////////////////////////////////////

        --Sincerely  Yours,--
      --\       SergeY      /--
    --<>\\\   PisarchiK   ///<>--  
 --<>()<>--Never surrendeR--<>()<>--
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[boost] lambda problem (VC7.0 and GNU Dev-C++)

Sergey Pisarchik