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From: Hyman Rosen <hymie@prolifics.com>
Subject: Re: Ada
Date: 2000/01/04
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Date: 2000-01-04T17:37:20+00:00
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Robert Dewar <robert_dewar@my-deja.com> writes:
> A pretty big gap! It means for example that if you have
> multiple implementations of sets, that you cannot have
> a parameterless function Empty that returns the (appropriate)
> empty set.

Incorrect as far as equivalent behavior is concerned,
as the following program demonstrates.

enum SetType { A, B, C };
template <SetType T> struct Set
{
	static Set Empty() { return Set(); }
};
struct EmptySet
{
	template <SetType T> operator Set<T>() { return Set<T>::Empty(); }
};
void f(Set<A>) { }
void g(Set<B>) { }
int main()
{
	f(EmptySet());
	g(EmptySet());
}