have a prefix even for tools to avoid the I for Info next to a verb looking off

console_logging.go

@@ -71,6 +71,18 @@ var (
 		Colors.Red,
 		Colors.Purple,
 		Colors.BrightRed,
+		Colors.Green, // NoLevel log.Printf
+	}
+	// Used for color version of console logging.
+	LevelToText = []string{
+		"Debg",
+		"Verb",
+		"Info",
+		"Warn",
+		"Err!",
+		"Crit",
+		"Fatal",
+		"",
 	}
 	// Cached flag for whether to use color output or not.
 	Color = false
@@ -106,6 +118,7 @@ func SetColorMode() {
 		Colors.Red,
 		Colors.Purple,
 		Colors.BrightRed,
+		Colors.Green, // NoLevel log.Printf
 	}
 }
 
@@ -130,3 +143,11 @@ func colorGID() string {
 	}
 	return Colors.Gray + fmt.Sprintf("[%d] ", goroutine.ID())
 }
+
+// Longer version when colorizing on console of the level text.
+func ColorLevelToStr(lvl Level) string {
+	if lvl == NoLevel {
+		return Colors.DarkGray
+	}
+	return LevelToColor[lvl] + LevelToText[lvl] + Colors.DarkGray
+}

levelsDemo/levels.go

@@ -15,7 +15,7 @@ func main() {
 	// Meat of the example: (some of these are reproducing fixed issues in `logc` json->console attributes detection)
 	log.Debugf("This is a debug message ending with backslash \\")
 	log.LogVf("This is a verbose message")
-	log.Printf("This an always printed, file:line omitted message")
+	log.Printf("This an always printed, file:line omitted message (and no level in console)")
 	log.Infof("This is an info message with no attributes but with \"quotes\"...")
 	log.S(log.Info, "This is multi line\n\tstructured info message with 3 attributes",
 		log.Str("attr1", "value1"), log.Attr("attr2", 42), log.Str("attr3", "\"quoted\nvalue\""))

logger.go

@@ -49,6 +49,7 @@ const (
 	Error
 	Critical
 	Fatal
+	NoLevel
 )
 
 //nolint:revive // we keep "Config" for the variable itself.
@@ -109,6 +110,7 @@ var (
 		"\"err\"",
 		"\"crit\"",
 		"\"fatal\"",
+		"\"info\"", // For Printf / NoLevel JSON output
 	}
 	// Reverse mapping of level string used in JSON to Level. Used by https://github.com/fortio/logc
 	// to interpret and colorize pre existing JSON logs.
@@ -120,7 +122,7 @@ var (
 // Needs to be called before flag.Parse(). Caller could also use log.Printf instead of changing this
 // if not wanting to use levels. Also makes log.Fatalf just exit instead of panic.
 func SetDefaultsForClientTools() {
-	Config.LogPrefix = ""
+	Config.LogPrefix = "> "
 	Config.LogFileAndLine = false
 	Config.FatalPanics = false
 	Config.ConsoleColor = true
@@ -159,13 +161,13 @@ func (l *JSONEntry) Time() time.Time {
 func init() {
 	setLevel(Info) // starting value
 	levelToStrM = make(map[string]Level, 2*len(LevelToStrA))
-	JSONStringLevelToLevel = make(map[string]Level, len(LevelToJSON))
+	JSONStringLevelToLevel = make(map[string]Level, len(LevelToJSON)-1) // -1 to not reverse info to NoLevel
 	for l, name := range LevelToStrA {
 		// Allow both -loglevel Verbose and -loglevel verbose ...
 		levelToStrM[name] = Level(l)
 		levelToStrM[strings.ToLower(name)] = Level(l)
 	}
-	for l, name := range LevelToJSON {
+	for l, name := range LevelToJSON[0 : Fatal+1] { // Skip NoLevel
 		// strip the quotes around
 		JSONStringLevelToLevel[name[1:len(name)-1]] = Level(l)
 	}
@@ -353,36 +355,46 @@ func logPrintf(lvl Level, format string, rest ...interface{}) {
 }
 
 func logUnconditionalf(logFileAndLine bool, lvl Level, format string, rest ...interface{}) {
+	prefix := Config.LogPrefix
+	if prefix == "" {
+		prefix = " "
+	}
+	lvl1Char := ""
+	if lvl == NoLevel {
+		prefix = ""
+	} else {
+		lvl1Char = LevelToStrA[lvl][0:1]
+	}
 	if logFileAndLine { //nolint:nestif
 		_, file, line, _ := runtime.Caller(3)
 		file = file[strings.LastIndex(file, "/")+1:]
 		if Color {
-			jsonWrite(fmt.Sprintf("%s%s%s%s %s:%d%s%s%s\n",
-				colorTimestamp(), colorGID(), LevelToColor[lvl], LevelToStrA[lvl][0:1],
-				file, line, Config.LogPrefix, fmt.Sprintf(format, rest...), Colors.Reset))
+			jsonWrite(fmt.Sprintf("%s%s%s %s:%d%s%s%s%s\n",
+				colorTimestamp(), colorGID(), ColorLevelToStr(lvl),
+				file, line, prefix, LevelToColor[lvl], fmt.Sprintf(format, rest...), Colors.Reset))
 		} else if Config.JSON {
 			jsonWrite(fmt.Sprintf("{%s\"level\":%s,%s\"file\":%q,\"line\":%d,\"msg\":%q}\n",
 				jsonTimestamp(), LevelToJSON[lvl], jsonGID(), file, line, fmt.Sprintf(format, rest...)))
 		} else {
-			log.Print(LevelToStrA[lvl][0:1], " ", file, ":", line, Config.LogPrefix, fmt.Sprintf(format, rest...))
+			log.Print(lvl1Char, " ", file, ":", line, prefix, fmt.Sprintf(format, rest...))
 		}
 	} else {
 		if Color {
-			jsonWrite(fmt.Sprintf("%s%s%s%s %s%s%s\n",
-				colorTimestamp(), colorGID(), LevelToColor[lvl], LevelToStrA[lvl][0:1], Config.LogPrefix,
+			jsonWrite(fmt.Sprintf("%s%s%s%s%s%s%s\n",
+				colorTimestamp(), colorGID(), ColorLevelToStr(lvl), prefix, LevelToColor[lvl],
 				fmt.Sprintf(format, rest...), Colors.Reset))
 		} else if Config.JSON {
 			jsonWrite(fmt.Sprintf("{%s\"level\":%s,%s\"msg\":%q}\n",
 				jsonTimestamp(), LevelToJSON[lvl], jsonGID(), fmt.Sprintf(format, rest...)))
 		} else {
-			log.Print(LevelToStrA[lvl][0:1], " ", Config.LogPrefix, fmt.Sprintf(format, rest...))
+			log.Print(lvl1Char, prefix, fmt.Sprintf(format, rest...))
 		}
 	}
 }
 
 // Printf forwards to the underlying go logger to print (with only timestamp prefixing).
 func Printf(format string, rest ...interface{}) {
-	logUnconditionalf(false, Info, format, rest...)
+	logUnconditionalf(false, NoLevel, format, rest...)
 }
 
 // SetOutput sets the output to a different writer (forwards to system logger).
@@ -539,28 +551,38 @@ func S(lvl Level, msg string, attrs ...KeyVal) {
 		buf.WriteString(fmt.Sprintf(format, attr.Key, attr.Value.String()))
 	}
 	// TODO share code with log.logUnconditionalf yet without extra locks or allocations/buffers?
+	prefix := Config.LogPrefix
+	if prefix == "" {
+		prefix = " "
+	}
+	lvl1Char := ""
+	if lvl == NoLevel {
+		prefix = ""
+	} else {
+		lvl1Char = LevelToStrA[lvl][0:1]
+	}
 	if Config.LogFileAndLine { //nolint:nestif
 		_, file, line, _ := runtime.Caller(1)
 		file = file[strings.LastIndex(file, "/")+1:]
 		if Color {
-			jsonWrite(fmt.Sprintf("%s%s%s%s %s:%d%s%s%s%s\n",
-				colorTimestamp(), colorGID(), LevelToColor[lvl], LevelToStrA[lvl][0:1],
-				file, line, Config.LogPrefix, msg, buf.String(), Colors.Reset))
+			jsonWrite(fmt.Sprintf("%s%s%s %s:%d%s%s%s%s%s\n",
+				colorTimestamp(), colorGID(), ColorLevelToStr(lvl),
+				file, line, prefix, LevelToColor[lvl], msg, buf.String(), Colors.Reset))
 		} else if Config.JSON {
 			jsonWrite(fmt.Sprintf("{%s\"level\":%s,%s\"file\":%q,\"line\":%d,\"msg\":%q%s}\n",
 				jsonTimestamp(), LevelToJSON[lvl], jsonGID(), file, line, msg, buf.String()))
 		} else {
-			log.Print(LevelToStrA[lvl][0:1], " ", file, ":", line, Config.LogPrefix, msg, buf.String())
+			log.Print(lvl1Char, " ", file, ":", line, prefix, msg, buf.String())
 		}
 	} else {
 		if Color {
-			jsonWrite(fmt.Sprintf("%s%s%s%s %s%s%s%s\n",
-				colorTimestamp(), colorGID(), LevelToColor[lvl], LevelToStrA[lvl][0:1], Config.LogPrefix, msg, buf.String(), Colors.Reset))
+			jsonWrite(fmt.Sprintf("%s%s%s%s%s%s%s%s\n",
+				colorTimestamp(), colorGID(), ColorLevelToStr(lvl), prefix, LevelToColor[lvl], msg, buf.String(), Colors.Reset))
 		} else if Config.JSON {
 			jsonWrite(fmt.Sprintf("{%s\"level\":%s,\"msg\":%q%s}\n",
 				jsonTimestamp(), LevelToJSON[lvl], msg, buf.String()))
 		} else {
-			log.Print(LevelToStrA[lvl][0:1], " ", Config.LogPrefix, msg, buf.String())
+			log.Print(lvl1Char, prefix, msg, buf.String())
 		}
 	}
 }

logger_test.go

@@ -59,7 +59,7 @@ func TestLoggerFilenameLine(t *testing.T) {
 	expected := "D logger_test.go:51-prefix-test\n" +
 		"E logger_test.go:53-prefix-SetLogLevel called with level -1 lower than Debug!\n" +
 		"I logger_test.go:54-prefix-Log level is now 3 Warning (was 0 Debug)\n" +
-		"I -prefix-Should show despite being Info - unconditional Printf without line/file\n"
+		"Should show despite being Info - unconditional Printf without line/file\n"
 	if actual != expected {
 		t.Errorf("unexpected:\n%s\nvs:\n%s\n", actual, expected)
 	}
@@ -111,7 +111,7 @@ func Test_LogS_JSON_no_json_with_filename(t *testing.T) {
 	_ = w.Flush()
 	actual := b.String()
 	expected := "W logger_test.go:109-bar-This will show, key1=\"value 1\", key2=\"42\"\n" +
-		"I -bar-This will show too\n"
+		"This will show too\n"
 	if actual != expected {
 		t.Errorf("got %q expected %q", actual, expected)
 	}
@@ -128,27 +128,28 @@ func TestColorMode(t *testing.T) {
 	Config = DefaultConfig()
 	Config.ForceColor = true
 	Config.NoTimestamp = true
+	Config.LogPrefix = "" // test it'll be at least one space
 	SetLogLevelQuiet(Info)
 	var b bytes.Buffer
 	w := bufio.NewWriter(&b)
 	SetOutput(w) // will call SetColorMode()
 	if !Color {
 		t.Errorf("expected to be in color mode after ForceColor=true and SetColorMode()")
 	}
-	S(Warning, "With file and line", Str("attr", "value with space")) // line 138
-	Infof("info with file and line = %v", Config.LogFileAndLine)      // line 139
+	S(Warning, "With file and line", Str("attr", "value with space")) // line 139
+	Infof("info with file and line = %v", Config.LogFileAndLine)      // line 140
 	Config.LogFileAndLine = false
 	Config.GoroutineID = false
 	S(Warning, "Without file and line", Str("attr", "value with space"))
 	Infof("info with file and line = %v", Config.LogFileAndLine)
 	_ = w.Flush()
 	actual := b.String()
 	grID := fmt.Sprintf("[%d] ", goroutine.ID())
-	expected := "\x1b[37m" + grID +
-		"\x1b[33mW logger_test.go:138> With file and line\x1b[0m, \x1b[34mattr\x1b[0m=\x1b[33m\"value with space\"\x1b[0m\n" +
-		"\x1b[37m" + grID + "\x1b[32mI logger_test.go:139> info with file and line = true\x1b[0m\n" +
-		"\x1b[33mW > Without file and line\x1b[0m, \x1b[34mattr\x1b[0m=\x1b[33m\"value with space\"\x1b[0m\n" +
-		"\x1b[32mI > info with file and line = false\x1b[0m\n"
+	expected := "\x1b[37m" + grID + "\x1b[33mWarn\x1b[90m logger_test.go:139 " +
+		"\x1b[33mWith file and line\x1b[0m, \x1b[34mattr\x1b[0m=\x1b[33m\"value with space\"\x1b[0m\n" +
+		"\x1b[37m" + grID + "\x1b[32mInfo\x1b[90m logger_test.go:140 \x1b[32minfo with file and line = true\x1b[0m\n" +
+		"\x1b[33mWarn\x1b[90m \x1b[33mWithout file and line\x1b[0m, \x1b[34mattr\x1b[0m=\x1b[33m\"value with space\"\x1b[0m\n" +
+		"\x1b[32mInfo\x1b[90m \x1b[32minfo with file and line = false\x1b[0m\n"
 	if actual != expected {
 		t.Errorf("got:\n%q\nexpected:\n%q", actual, expected)
 	}
@@ -258,7 +259,7 @@ func TestLogger1(t *testing.T) {
 	Critf("testing crit %d", i) // should show
 	expected += "C testing crit 7\n"
 	Printf("Printf should always show n=%d", 8)
-	expected += "I Printf should always show n=8\n"
+	expected += "Printf should always show n=8\n"
 	r := FErrf("FErrf should always show but not exit, n=%d", 9)
 	expected += "F FErrf should always show but not exit, n=9\n"
 	if r != 1 {
@@ -277,7 +278,7 @@ func TestLoggerJSON(t *testing.T) {
 	w := bufio.NewWriter(&b)
 	SetLogLevel(LevelByName("Verbose"))
 	Config.LogFileAndLine = true
-	Config.LogPrefix = "no used"
+	Config.LogPrefix = "not used"
 	Config.JSON = true
 	Config.NoTimestamp = false
 	SetOutput(w)
@@ -420,9 +421,11 @@ func Test_LogS_JSON_no_json_no_file(t *testing.T) {
 	// Start of the actual test
 	S(Verbose, "This won't show")
 	S(Warning, "This will show", Str("key1", "value 1"), Attr("key2", 42))
+	S(NoLevel, "This NoLevel will show despite logically info level")
 	_ = w.Flush()
 	actual := b.String()
-	expected := "W -foo-This will show, key1=\"value 1\", key2=\"42\"\n"
+	expected := "W-foo-This will show, key1=\"value 1\", key2=\"42\"\n" +
+		"This NoLevel will show despite logically info level\n"
 	if actual != expected {
 		t.Errorf("got %q expected %q", actual, expected)
 	}
@@ -670,6 +673,36 @@ func TestJSONLevelReverse(t *testing.T) {
 	if lvl != Warning {
 		t.Errorf("unexpected level %d", lvl)
 	}
+	lvl = JSONStringLevelToLevel["info"] // Should be info and not NoLevel (7)
+	if lvl != Info {
+		t.Errorf("unexpected level %d", lvl)
+	}
+	lvl = JSONStringLevelToLevel["fatal"] // Should be info and not NoLevel (7)
+	if lvl != Fatal {
+		t.Errorf("unexpected level %d", lvl)
+	}
+}
+
+func TestNoLevel(t *testing.T) {
+	Config.ForceColor = true
+	SetColorMode()
+	color := ColorLevelToStr(NoLevel)
+	if color != ANSIColors.DarkGray {
+		t.Errorf("unexpected color %q", color)
+	}
+	Config.ForceColor = false
+	Config.JSON = true
+	Config.ConsoleColor = false
+	Config.NoTimestamp = true
+	Config.GoroutineID = false
+	var buf bytes.Buffer
+	SetOutput(&buf)
+	Printf("test")
+	actual := buf.String()
+	expected := `{"level":"info","msg":"test"}` + "\n"
+	if actual != expected {
+		t.Errorf("unexpected:\n%s\nvs:\n%s\n", actual, expected)
+	}
 }
 
 // io.Discard but specially known to by logger optimizations for instance.