Create a disengaged optional object if the specified original object is disengaged, and an optional object with the value of original.value().
Declared in <bslstl_optional.h>
template<class t_ANY_TYPE>
optional(
std::allocator_arg_t allocatorArg,
AllocType allocator,
std::optional<t_ANY_TYPE> const& original);Create a disengaged optional object if the specified original object is disengaged, and an optional object with the value of original.value() converted
Create a disengaged optional object if the specified original object is disengaged, and an optional object with the value of original.value() converted to t_TYPE otherwise. Use the specified allocator to supply memory. Note that this constructor participates in overload resolution only when t_TYPE is constructible from an lvalue of const t_ANY_TYPE, and is implicit only when an lvalue of const t_ANY_TYPE is implicitly convertible to t_TYPE.
| Name | Description |
|---|---|
| allocatorArg | tag selecting the allocator-extended constructor |
| allocator | allocator used to supply memory |
| original | source optional used to initialize this object |