Re: [boost] Re: "invariants" class; Version 1.00

From: Daniel Wallin (dalwan01_at_[hidden])
Date: 2004-01-08 17:35:50

Dan W. wrote:
> Daniel Wallin wrote:
> 
>> Consider:
>>
>>   template<class T>
>>   struct B
>>   {
>>       struct type {};
>>   };
>>
>>   template<class T>
>>   struct A : B<A<T> >
>>   {
>>       typedef typename B<A<T> >::type type;
>>        dependent, needs typename ^^^^
>>   };
> 
> 
>     template<class T>
>     struct A : private B< A<T> >
>     {
>      private:
>         //no typedefing OR typenaming,
>         //as trigobj is not for export;
>         //--just using type as in...
>         type _typo;
>      public:
>         //or...
>         void f()
>         {
>             type a_typo;
>         }
>         //isn't this compliant?
>         ...
>     };

I don't know what you are doing here, but it isn't the same thing that
you are doing in your invariants<> class. Just try compiling your own
examples with a standard conforming compiler. The nested trigobj class
needs to be referenced with typename if used in a class template.

   template<class T>
   struct B
   {
      struct type {};
   };

   template<class T>
   struct A : B<A<T> >
   {
      void f()
      {
          /* typename */ B<A<T> >::type x;
          /* ^^^^^^^^ needed here */
      }
   };

   int main()
   {
      A<int> y;
      y.f();
   }

You can try this example, which does the same thing that your code
does, out at:

   http://www.comeaucomputing.com/tryitout/

-- 
Daniel Wallin