Template question

[Frits van Bommel]

Michiel wrote:
> But the user of the function should also have the option to use it like
> this:
> 
> auto x = set!(int);
> 
> To create the empty set (that can hold int). How can I implement this?

What's wrong with "auto x = new Set!(int);"? It's how every other class 
type is instantiated.

An alternative would be to make your set type a struct instead of a 
class, then you could just have "Set!(int) x;" declare an empty set.
You'd have to be careful about the copying behavior though, structs are 
copied by value, not reference. But if the struct contained a 
reference/pointer to the actual data, it could work.

> PS: I would have liked to skip the type altogether for the empty set,
> but the problem appears when you want to put something inside that set.
> I've considered using a dummy type and to somehow construct the correct
> set-type after the first insert, but it wouldn't be consistent with
> normal sets and altogether too much trouble.

This would probably be a bad idea in a statically typed language. It 
could be made to work, but that would require you to specify the type 
whenever you wanted to extract an element from the set...