add some useful methods

default_logger.go

@@ -2,12 +2,17 @@ package mlog
 
 import (
 	"fmt"
+	"io"
 	"os"
 )
 
 // DefaultLogger is the default package level Logger
 var DefaultLogger = New(os.Stderr, Lstd)
 
+func SetOutput(writer io.Writer) {
+	DefaultLogger.SetOutput(writer)
+}
+
 // SetEmitter sets the Emitter for the degault logger. See
 // Logger.SetEmitter.
 func SetEmitter(e Emitter) {

logger.go

@@ -26,6 +26,13 @@ type Logger struct {
 	flags uint64
 }
 
+func (l *Logger) SetOutput(writer io.Writer) {
+	// lock writing to serialize log output (no scrambled log lines)
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.out = writer
+}
+
 func (l *Logger) Write(b []byte) (int, error) {
 	// lock writing to serialize log output (no scrambled log lines)
 	l.mu.Lock()