[#bsl-variant-2constructor-0e]
= xref:bsl.adoc[bsl]::xref:bsl/variant.adoc[variant]::variant
:relfileprefix: ../../
:mrdocs:

Constructors

== Synopses

Declared in `<bslstl_variant.h>`

Create a `variant` object holding a value‐initialized 0th alternative.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_FIRST_ALT = t_HEAD>
requires std::is_default_constructible<t_FIRST_ALT>::value
xref:bsl/variant/2constructor-06.adoc[variant]();
----

[.small]#xref:bsl/variant/2constructor-06.adoc[_» more..._]#

Create a `variant` object holding a copy of `original`'s alternative.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/variant/2constructor-034.adoc[variant](xref:bsl/variant.adoc[variant] const& original) = default;
----

[.small]#xref:bsl/variant/2constructor-034.adoc[_» more..._]#

Create a `variant` object holding a moved copy of `original`'s alternative.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/variant/2constructor-07a.adoc[variant](xref:bsl/variant.adoc[variant]&& original) = default;
----

[.small]#xref:bsl/variant/2constructor-07a.adoc[_» more..._]#

Create a `variant` object from a `std::variant` `original`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_STD_VARIANT>
explicit
xref:bsl/variant/2constructor-011.adoc[variant](t_STD_VARIANT&& original);
----

[.small]#xref:bsl/variant/2constructor-011.adoc[_» more..._]#

Create a `variant` object whose contained value is initialized from `t`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_TYPE>
xref:bsl/variant/2constructor-04.adoc[variant](t_TYPE&& t);
----

[.small]#xref:bsl/variant/2constructor-04.adoc[_» more..._]#

Create a `variant` object holding a value‐initialized 0th alternative using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_FIRST = t_HEAD>
requires std::is_default_constructible<t_FIRST>::value
xref:bsl/variant/2constructor-015.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator);
----

[.small]#xref:bsl/variant/2constructor-015.adoc[_» more..._]#

Create a `variant` object holding the `t_INDEX` alternative from `args`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    std::size_t t_INDEX,
    class... t_ARGS>
requires (t_INDEX < 1 + sizeof...(t_TAIL)) &&
                  std::is_constructible<BSLSTL_VARIANT_TYPE_AT_INDEX(t_INDEX),
                                        t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-018.adoc[variant](
    bsl::in_place_index_t<t_INDEX> inPlaceIndex,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-018.adoc[_» more..._]#

Create a `variant` object holding a `t_TYPE` alternative from `args`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_TYPE,
    class... t_ARGS>
requires BSLSTL_VARIANT_HAS_UNIQUE_TYPE(t_TYPE) &&
                  std::is_constructible<t_TYPE, t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-0d1.adoc[variant](
    bsl::in_place_type_t<t_TYPE> inPlaceType,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-0d1.adoc[_» more..._]#

Create a `variant` object holding a copy of `original`'s alternative using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_FIRST = t_HEAD>
requires BloombergLP::bslstl::
                Variant_IsCopyConstructibleAll<t_FIRST, t_TAIL...>::value
xref:bsl/variant/2constructor-0b.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    xref:bsl/variant.adoc[variant] const& original);
----

[.small]#xref:bsl/variant/2constructor-0b.adoc[_» more..._]#

Create a `variant` object from a `std::variant` `original` using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_STD_VARIANT>
explicit
xref:bsl/variant/2constructor-07b.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    t_STD_VARIANT&& original);
----

[.small]#xref:bsl/variant/2constructor-07b.adoc[_» more..._]#

Create a `variant` object whose contained value is initialized from `t` using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_TYPE>
xref:bsl/variant/2constructor-030.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    t_TYPE&& t);
----

[.small]#xref:bsl/variant/2constructor-030.adoc[_» more..._]#

Create a `variant` object holding a moved copy of `original`'s alternative using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_FIRST = t_HEAD>
requires BloombergLP::bslstl::
                Variant_IsMoveConstructibleAll<t_FIRST, t_TAIL...>::value
xref:bsl/variant/2constructor-026.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    xref:bsl/variant.adoc[variant]&& original);
----

[.small]#xref:bsl/variant/2constructor-026.adoc[_» more..._]#

Create a `variant` object holding the `t_INDEX` alternative from `il` and `args`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    std::size_t t_INDEX,
    class INIT_LIST_TYPE,
    class... t_ARGS>
requires (t_INDEX < 1 + sizeof...(t_TAIL)) &&
                  std::is_constructible<BSLSTL_VARIANT_TYPE_AT_INDEX(t_INDEX),
                                        std::initializer_list<INIT_LIST_TYPE>&,
                                        t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-09.adoc[variant](
    bsl::in_place_index_t<t_INDEX> inPlaceIndex,
    std::initializer_list<INIT_LIST_TYPE> il,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-09.adoc[_» more..._]#

Create a `variant` object holding a `t_TYPE` alternative from `il` and `args`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_TYPE,
    class INIT_LIST_TYPE,
    class... t_ARGS>
requires BSLSTL_VARIANT_HAS_UNIQUE_TYPE(t_TYPE) &&
                  std::is_constructible<t_TYPE,
                                        std::initializer_list<INIT_LIST_TYPE>&,
                                        t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-033.adoc[variant](
    bsl::in_place_type_t<t_TYPE> inPlaceType,
    std::initializer_list<INIT_LIST_TYPE> il,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-033.adoc[_» more..._]#

Create a `variant` object holding the `t_INDEX` alternative from `args` using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    std::size_t t_INDEX,
    class... t_ARGS>
requires (t_INDEX < 1 + sizeof...(t_TAIL)) &&
                  std::is_constructible<BSLSTL_VARIANT_TYPE_AT_INDEX(t_INDEX),
                                        t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-07fa.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    bsl::in_place_index_t<t_INDEX> inPlaceIndex,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-07fa.adoc[_» more..._]#

Create a `variant` object holding a `t_TYPE` alternative from `args` using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_TYPE,
    class... t_ARGS>
requires BSLSTL_VARIANT_HAS_UNIQUE_TYPE(t_TYPE) &&
                  std::is_constructible<t_TYPE, t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-0d0.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    bsl::in_place_type_t<t_TYPE> inPlaceType,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-0d0.adoc[_» more..._]#

Create a `variant` object holding the `t_INDEX` alternative from `il` and `args` using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    std::size_t t_INDEX,
    class INIT_LIST_TYPE,
    class... t_ARGS>
requires (t_INDEX < 1 + sizeof...(t_TAIL)) &&
                  std::is_constructible<BSLSTL_VARIANT_TYPE_AT_INDEX(t_INDEX),
                                        std::initializer_list<INIT_LIST_TYPE>&,
                                        t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-07f8.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    bsl::in_place_index_t<t_INDEX> inPlaceIndex,
    std::initializer_list<INIT_LIST_TYPE> il,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-07f8.adoc[_» more..._]#

Create a `variant` object holding a `t_TYPE` alternative from `il` and `args` using `allocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_TYPE,
    class INIT_LIST_TYPE,
    class... t_ARGS>
requires BSLSTL_VARIANT_HAS_UNIQUE_TYPE(t_TYPE) &&
                  std::is_constructible<t_TYPE,
                                        std::initializer_list<INIT_LIST_TYPE>&,
                                        t_ARGS...>::value
explicit
xref:bsl/variant/2constructor-02d.adoc[variant](
    std::allocator_arg_t allocatorArg,
    xref:bsl/variant/allocator_type.adoc[allocator_type] allocator,
    bsl::in_place_type_t<t_TYPE> inPlaceType,
    std::initializer_list<INIT_LIST_TYPE> il,
    t_ARGS&&... args);
----

[.small]#xref:bsl/variant/2constructor-02d.adoc[_» more..._]#

== Parameters

[cols="1,4"]
|===
| Name| Description
| *original*
| variant to copy
| *t*
| value used to initialize the selected alternative
| *allocatorArg*
| tag selecting the allocator‐extended overload
| *allocator*
| allocator used to supply memory
| *inPlaceIndex*
| tag selecting the `t_INDEX` alternative
| *args*
| arguments used to construct the selected alternative
| *inPlaceType*
| tag selecting the `t_TYPE` alternative
| *il*
| initializer list used to construct the selected alternative
|===


[.small]#Created with https://www.mrdocs.com[MrDocs]#