std::variant
suggest changeVariant is a replacement for raw union
use. It is type-safe and knows what type it is, and it carefully constructs and destroys the objects within it when it should.
It is almost never empty: only in corner cases where replacing its content throws and it cannot back out safely does it end up being in an empty state.
It behaves somewhat like a std::tuple
, and somewhat like an std::optional
.
Using std::get
and std::get_if
is usually a bad idea. The right answer is usually std::visit
, which lets you deal with every possibility right there. if constexpr
can be used within the visit
if you need to branch your behavior, rather than doing a sequence of runtime checks that duplicate what visit
will do more efficiently.
Found a mistake? Have a question or improvement idea?
Let me know.
Table Of Contents