ios_base::event

typedef T5 event;
static const event copyfmt_event, erase_event,
    imbue_event;

The type is an enumerated type T5 that describes an object that can store the callback event used as an argument to a function registered with register_callback. The distinct event values are:

• copyfmt_event, to identify a callback that occurs near the end of a call to copyfmt, just before the exception mask is copied.
• erase_event, to identify a callback that occurs at the beginning of a call to copyfmt, or at the beginning of a call to the destructor for *this.
• imbue_event, to identify a callback that occurs at the end of a call to imbue, just before the function returns.