Variants
(ply-system.h)

A Variant can hold a value of one of several predefined types at runtime. It's similar to a tagged union.

template <typename... Types> class Variant;

template <typename T> Variant::Variant(T&& value)

Constructs a variant containing the given value. T must be one of the variant's allowed types.

template <typename T> Variant& Variant::operator=(T&& value)

Assigns a new value to the variant. The previous value is destroyed first.

u32 Variant::getSubtypeIndex() const

Returns the zero-based index of the currently held type within the variant's type list.

bool Variant::isEmpty() const

Returns true if the variant holds no value.

template <typename T> bool Variant::is() const

Returns true if the variant currently holds a value of type T.

template <typename T> T* Variant::as()
template <typename T> const T* Variant::as() const

Returns a pointer to the contained value if it's of type T, or nullptr otherwise.

template <typename T, typename... Args> T& Variant::switchTo(Args&& args)

Destroys the current value (if any), constructs a new value of type T using the provided arguments, and returns a reference to it.

Variant<int, String, float> value;
value = 42;
if (value.is<int>()) {
    int* p = value.as<int>();  // Points to the int.
}
value.switchTo<String>("hello");