[#mp_units-quantity_point-08-operator_minus_eq]
= xref:mp_units.adoc[mp_units]::xref:mp_units/quantity_point-08.adoc[quantity_point]::operator‐=
:relfileprefix: ../../
:mrdocs:

Subtraction assignment operator

== Synopsis

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

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    auto R2,
    typename Rep2>
requires (implicitly_convertible(get_quantity_spec(R2), quantity_spec)) &&
            detail::ValuePreservingConversion<get_unit(R2), Rep2, unit, rep> &&
            requires(const quantity_type q) { quantity_from_origin_is_an_implementation_detail_ ‐= q; }
constexpr
xref:mp_units/quantity_point-08.adoc[quantity_point]&
operator‐=(xref:mp_units/quantity-01.adoc[quantity<R2, Rep2>] const& q) &;
----

== Return Value

Reference to the current object

== Parameters

[cols=2]
|===
| Name
| Description
| *q*
| The right operand
|===


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