Re: class nested in template class: Dev-C works while VC6 not

From:
"Igor Tandetnik" <itandetnik@mvps.org>
Newsgroups:
microsoft.public.vc.language
Date:
Thu, 2 Jul 2009 16:14:07 -0400
Message-ID:
<uJ3toG1#JHA.1740@TK2MSFTNGP02.phx.gbl>
LiDongning <lidongning@gmail.com> wrote:

I am trying to create a class nested in a template. Following piece of
codes works in Dev-C but can not be complied in VC6 with following
error message.

error LNK2001: unresolved external symbol "public: __thiscall
Ta<double>::Tb::Tb(double)" (??0Tb@?$Ta@N@@QAE@N@Z)


VC6 has a very limited support for templates. You often need to tweak
and simplify to keep it happy.

template <class T>
class Ta
{
public:
      class Tb
      {
      public:
             T x;
             Tb(T=T(0));
      };
      Tb u;

};

template <class T>
Ta<T>::Tb::Tb(T inx):x(inx)
{
     }


Try defining the constructor in-class. I seem to remember VC6 doesn't
support out-of-class definitions.

template <class T>
class Ta
{
public:
       class Tb
       {
       public:
              T x;
              Tb(T inx=T(0)) : x(inx) {}
       };
       Tb u;
};

--
With best wishes,
    Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925

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