26 Localization library [localization]

26.4 Standard locale categories [locale.categories]

26.4.7 The message retrieval category [category.messages]

26.4.7.1 Class template messages [locale.messages]

26.4.7.1.2 Virtual functions [locale.messages.virtuals]

catalog do_open(const basic_string<char>& name, const locale& loc) const;
Returns: A value that may be passed to get() to retrieve a message from the message catalog identified by the string name according to an implementation-defined mapping.
The result can be used until it is passed to close().
Returns a value less than 0 if no such catalog can be opened.
Remarks: The locale argument loc is used for character set code conversion when retrieving messages, if needed.
string_type do_get(catalog cat, int set, int msgid, const string_type& dfault) const;
Requires: cat shall be a catalog obtained from open() and not yet closed.
Returns: A message identified by arguments set, msgid, and dfault, according to an implementation-defined mapping.
If no such message can be found, returns dfault.
void do_close(catalog cat) const;
Requires: cat shall be a catalog obtained from open() and not yet closed.
Effects: Releases unspecified resources associated with cat.
Remarks: The limit on such resources, if any, is implementation-defined.