I've just read the 'Implementing class templates' article by Michael Ball in
the September '93 C++ report. It mentions that the ANSI/ISO committee is
trying to tidy up templates in respect to their use of non-extern names and
the binding of names to different symbols depending on the location of
template instatiation.

I was thinking about the example given by Michael Ball in his column. The
example he gave was as follows:

 class strange
  {
  };

 class stranger
  {
  enum
   {
   intown
   };
  };

 class intown
  {
  };


 template <class T> class odd : public T
  {
  intown a;
  };


 odd<strange> ts;
 odd<stranger> tsr;



As he points out: The instantiations of the template-class odd implies that
member a has the following types:

 odd<strange>::a  has type   class intown
 odd<stranger>::a  has type   stranger::intown



Now to the point: The template-class odd is actually parameterized by two
types - namely T and intown - since intown can vary depending on T. Will such
'indirect parameterization' be disallowed in any revision of the template
standard?


Templates at the moment seem like a pre-processor extension (Borland C++
actually uses a similar technique - no syntax checking is performed until
template instantiation, not even syntax analysis). They create all-sorts of
problems for the compiler and especially any sort of high-level environment
that tries to intelligently help with the creation of template classes.

Ideally, the class-template must be parsed as much as possible when it is
first seen. This would bind any names used in the class-template to symbols.
Function definitions can be stored unparsed. When the template is
instantiated, a parameterized base class may add more members, but at least
the immediate template class members do not depend indirectly on the
parameter.


I hope this all makes sense. The current template-class specification is
causing me major headaches in the development environment for our compiler.


Comments or info appreciated.



--
Simon Huntington
Software Interrupt Developments. Leeds, UK.