std::locale::id (3) Linux Manual Page

std::locale::id – std::locale::id

Synopsis

Defined in header <locale>

class locale::id;

The class std::locale::id provides implementation-specific identification of a locale facet. Each class derived from std::locale::facet must have a public static member named id of type std::locale::id and each std::locale object maintains a list of facets it implements, indexed by their ids.
Facets with the same id belong to the same facet category and replace each other when added to a locale object.

Member functions

              constructs a new id
constructor (public member function)
              copy assignment operator is deleted
operator= (public member function)

Example

The following example shows how to construct a minimal custom facet.
// Run this code

#include <iostream>

#include <locale>
struct myfacet : std::locale::facet

{
    myfacet(std::size_t refs = 0)
        : facet(refs)
    {
    }
    static std::locale::id id;
};
std::locale::id myfacet::id;
int main()

{
    std::locale myloc(std::locale(), new myfacet);
    std::cout << "has_facet<myfacet>(myloc) returns " << std::boolalpha
              << std::has_facet<myfacet>(myloc) << '\n';
}

Output:

  has_facet<myfacet>(myloc) returns true

See also

      the base class for all facet categories: each facet of any category is derived from this type
facet (class)