std::locale::id (3) - Linux Manuals

std::locale::id: std::locale::id


std::locale::id - std::locale::id


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)


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';


  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)