🚀 go-pugleaf

In article <9532600.2461@mulga.cs.mu.OZ.AU>,
Fergus Henderson <fjh@munta.cs.mu.OZ.AU> wrote:
>Part of the problem is that the C++ language is not powerful enough to
>express the right exception specifications for even simple templates.
>For example, what should the exception specification for the following
>template be?
>
>	template <class T> T add3 (T a, T b, T c) { return a + b + c; }
>
I think you could in principle declare the exception specification as
typedefs, and then refer to the new types in the exception specification.
For example: (assuming all functions have a corresponding function object)

template <class Function> class exception_specification;
template <class T> class exception_specification<add3_function<T,T,T,T> >
{ // Here add3_function<> is a function object for add3
  typedef exception_specification<plus<T> >::spec spec;
};

template <class T> T add3(T a, T b, T c) 
throw (exception_specification<add3_function<T,T,T,T> >::spec)
{ return a + b + c; }

But this is very verbose, requires every user function to have a corresponding
exception specification specialization (in addition to a function object) 
and does get ugly when declaring multiple exception specifications for
a single function.
-- 
   Esa Pulkkinen                        | C++ programmers do it virtually
   E-Mail:  esap@cs.tut.fi              | everywhere with a class, resulting
   WWW   :  http://www.cs.tut.fi/~esap/ | in multiple inheritance.


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