package log import ( "time" "github.com/go-stack/stack" ) // A Valuer generates a log value. When passed to With or WithPrefix in a // value element (odd indexes), it represents a dynamic value which is re- // evaluated with each log event. type Valuer func() interface{} // bindValues replaces all value elements (odd indexes) containing a Valuer // with their generated value. func bindValues(keyvals []interface{}) { for i := 1; i < len(keyvals); i += 2 { if v, ok := keyvals[i].(Valuer); ok { keyvals[i] = v() } } } // containsValuer returns true if any of the value elements (odd indexes) // contain a Valuer. func containsValuer(keyvals []interface{}) bool { for i := 1; i < len(keyvals); i += 2 { if _, ok := keyvals[i].(Valuer); ok { return true } } return false } // Timestamp returns a Valuer that invokes the underlying function when bound, // returning a time.Time. Users will probably want to use DefaultTimestamp or // DefaultTimestampUTC. func Timestamp(t func() time.Time) Valuer { return func() interface{} { return t() } } // Caller returns a Valuer that returns a file and line from a specified depth // in the callstack. Users will probably want to use DefaultCaller. func Caller(depth int) Valuer { return func() interface{} { return stack.Caller(depth) } } var ( // DefaultTimestamp is a Valuer that returns the current wallclock time, // respecting time zones, when bound. DefaultTimestamp = Valuer(func() interface{} { return time.Now().Format(time.RFC3339Nano) }) // DefaultTimestampUTC is a Valuer that returns the current time in UTC // when bound. DefaultTimestampUTC = Valuer(func() interface{} { return time.Now().UTC().Format(time.RFC3339Nano) }) // DefaultCaller is a Valuer that returns the file and line where the Log // method was invoked. It can only be used with log.With. DefaultCaller = Caller(3) )