With regards to the paper which describes removing the void specializations for std::future and std::promise P0241R0. This may be a stupid question but the proposed solution is to remove the void specialization entirely, but then what are people expected to do when they want to instantiate a std::future<void>object?
Removing the void specializations for std::future and std::promise
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3 Answers
Having tinkered with implementing the TS, it seems possible to avoid specializing for void if the implementation does some clever things with enable_if, e.g.
template <class R>
R future<R>::get()
{
return shared().get();
}
template <class R>
class shared_state {
...
R get()
{
wait();
if constexpr (!std::is_same_v<V, void>) {
return *_value;
}
}
template <typename V = value_t, std::enable_if_t<!std::is_same_v<V, void>, V>* = nullptr>
void set_value(const V& value)
{
...
}
template <typename V = value_t, std::enable_if_t<std::is_same_v<V, void>, V>* = nullptr>
void set_value()
{
...
}
}
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