[#mp_units-quantity_point-08-2constructor-075]
= xref:mp_units.adoc[mp_units]::xref:mp_units/quantity_point-08.adoc[quantity_point]::quantity_point
:relfileprefix: ../../
:mrdocs:

Constructors

== Synopses

Declared in `<mp‐units/framework/quantity_point.h>`

Default constructor. Leaves the underlying quantity default‐initialized.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
[[nodiscard]]
xref:mp_units/quantity_point-08/2constructor-07e.adoc[quantity_point]() = default;
----

[.small]#xref:mp_units/quantity_point-08/2constructor-07e.adoc[_» more..._]#

Converting constructor from a quantity point anchored to a different absolute point origin.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<xref:mp_units/QuantityPoint.adoc[QuantityPoint] QP>
requires (!QuantityPointOf<QP, absolute_point_origin>) && requires(const QP& src) {
      { src.point_for(point_origin) } ‐> QuantityPointOf<point_origin>;
      quantity_type{src.point_for(point_origin) ‐ point_origin};
    }
[[nodiscard]]
constexpr
explicit
xref:mp_units/quantity_point-08/2constructor-09.adoc[quantity_point](QP const& qp);
----

[.small]#xref:mp_units/quantity_point-08/2constructor-09.adoc[_» more..._]#

Constructs a quantity point from an external quantity‐point‐like type via `quantity_point_like_traits`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<xref:mp_units/QuantityPointLike.adoc[QuantityPointLike] QP>
requires (quantity_point_like_traits<QP>::point_origin == point_origin) &&
            std::constructible_from<quantity_type, quantity<quantity_point_like_traits<QP>::reference,
                                                            typename quantity_point_like_traits<QP>::rep>>
[[nodiscard]]
constexpr
explicit(quantity_point_like_traits<QP>::explicit_import || !std::convertible_to<quantity<quantity_point_like_traits<QP>::reference, typename quantity_point_like_traits<QP>::rep>, quantity_type>)
xref:mp_units/quantity_point-08/2constructor-07c.adoc[quantity_point](QP const& qp);
----

[.small]#xref:mp_units/quantity_point-08/2constructor-07c.adoc[_» more..._]#

Converting constructor from another quantity point that shares this one's absolute point origin.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<xref:mp_units/QuantityPointOf.adoc[QuantityPointOf<absolute_point_origin>] QP>
requires std::constructible_from<quantity_type, typename QP::quantity_type>
[[nodiscard]]
constexpr
explicit(!std::convertible_to<typename QP::quantity_type, quantity_type>)
xref:mp_units/quantity_point-08/2constructor-00.adoc[quantity_point](QP const& qp);
----

[.small]#xref:mp_units/quantity_point-08/2constructor-00.adoc[_» more..._]#

Constructs a quantity point from a quantity, measured from the default point origin.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename FwdQ,
    xref:mp_units/QuantityOf.adoc[QuantityOf<quantity_spec>] Q = std::remove_cvref_t<FwdQ>>
requires std::constructible_from<quantity_type, FwdQ> && (point_origin == default_point_origin(R))
[[nodiscard]]
constexpr
explicit
xref:mp_units/quantity_point-08/2constructor-0b.adoc[quantity_point](FwdQ&& q);
----

[.small]#xref:mp_units/quantity_point-08/2constructor-0b.adoc[_» more..._]#

Constructs a quantity point from a quantity measured from this point's own origin.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename FwdQ,
    xref:mp_units/QuantityOf.adoc[QuantityOf<quantity_spec>] Q = std::remove_cvref_t<FwdQ>>
requires std::constructible_from<quantity_type, FwdQ>
[[nodiscard]]
constexpr
xref:mp_units/quantity_point-08/2constructor-02.adoc[quantity_point](
    FwdQ&& q,
    decltype(PO) po);
----

[.small]#xref:mp_units/quantity_point-08/2constructor-02.adoc[_» more..._]#

Constructs a quantity point from a quantity measured from another point origin that shares this one's absolute point origin.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename FwdQ,
    xref:mp_units/PointOrigin.adoc[PointOrigin] PO2,
    xref:mp_units/Quantity-0c.adoc[Quantity] Q = std::remove_cvref_t<FwdQ>>
requires PointOriginFor<PO2, Q::quantity_spec> && std::constructible_from<quantity_type, FwdQ> &&
             detail::SameAbsolutePointOriginAs<PO2, PO>
[[nodiscard]]
constexpr
xref:mp_units/quantity_point-08/2constructor-08.adoc[quantity_point](
    FwdQ&& q,
    PO2 po);
----

[.small]#xref:mp_units/quantity_point-08/2constructor-08.adoc[_» more..._]#

== Return Value

[NOTE]
====
The return value https://en.cppreference.com/cpp/language/attributes/nodiscard[should not be discarded^].
====
== Parameters

[cols="1,4"]
|===
| Name| Description
| *qp*
| the source quantity point to convert from
| *q*
| the quantity giving the offset from `point_origin`
| *po*
| the point origin the quantity is measured from, equal to `point_origin`
|===


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