[#mp_units-named_constant]
= xref:mp_units.adoc[mp_units]::named_constant
:relfileprefix: ../
:mrdocs:

Named constant definition

== Synopsis

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

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    xref:mp_units/symbol_text-032.adoc[symbol_text] Symbol,
    xref:mp_units/Unit.adoc[Unit] auto U>
requires (!Symbol.empty())
struct named_constant
    : ::_base_type_
----

== Description

It is very similar to `named_unit` but:

* allows negative exponents in the unit definition (TODO )
* does not allow the constant to be associated with a `quantity_spec`
* does not allow the constant to be prefixed

== Base Classes

[cols="1,4"]
|===
|Name|Description

| `::_base_type_`
| 
|===

== Types

[cols=1]
|===
| Name
| xref:mp_units/named_constant/_base_type_.adoc[`_base_type_`] 
|===

== Static Data Members

[cols="1,4"]
|===
| Name| Description
| xref:mp_units/named_constant/_symbol_.adoc[`_symbol_`] 
| Unique constant identifier
|===

== Derived Classes

[cols="1,4"]
|===
|Name|Description

| xref:mp_units/pi-0c.adoc[`pi`]
| 
|===

== Template Parameters

[cols="1,4"]
|===
|Name|Description

| *Symbol*
| a short text representation of the constant
| *Unit*
| a unit that we use to define a constant
|===


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