30 Localization library [localization]

30.4 Standard locale categories [locale.categories]

30.4.8 The message retrieval category [category.messages] Class template messages [locale.messages] General [locale.messages.general]

namespace std { class messages_base { public: using catalog = unspecified signed integer type; }; template<class charT> class messages : public locale::facet, public messages_base { public: using char_type = charT; using string_type = basic_string<charT>; explicit messages(size_t refs = 0); catalog open(const string& fn, const locale&) const; string_type get(catalog c, int set, int msgid, const string_type& dfault) const; void close(catalog c) const; static locale::id id; protected: ~messages(); virtual catalog do_open(const string&, const locale&) const; virtual string_type do_get(catalog, int set, int msgid, const string_type& dfault) const; virtual void do_close(catalog) const; }; }
Values of type messages_base​::​catalog usable as arguments to members get and close can be obtained only by calling member open.