(new): prepare v2.1.0 release

- add custom LogLevel constructors and richer color configuration
- support ANSI, 256-color, RGB, and text attributes on LogLevel
- introduce clearer preferred APIs such as NewLogger and SetName
- preserve backward compatibility with deprecated wrappers for v2.0.1 APIs
- restore legacy ColorStringBuilder signatures as compatibility wrappers
- fix newline separator handling in Println-style output
- add tests for color precedence, deprecated aliases, and LogLevel attributes
- update GoDoc and bilingual README documentation

writers.go

@@ -17,6 +17,20 @@ type LoggerWriter interface {
 	Print(level LogLevel, prefix string, traceback []*MethodTraceback, messages ...any) error
 }
 
+// PrepareMessages normalizes message parts and extracts a trailing newline marker.
+func PrepareMessages(messages ...any) (bool, []any) {
+	msg := Map(messages, func(el any) string { return fmt.Sprint(el) })
+	newline := false
+	if len(msg) > 0 && strings.HasSuffix(msg[len(msg)-1], "\n") {
+		newline = true
+		msg[len(msg)-1] = strings.TrimSuffix(msg[len(msg)-1], "\n")
+		if msg[len(msg)-1] == "" {
+			msg = msg[:len(msg)-1]
+		}
+	}
+	return newline, Map(msg, func(el string) any { return any(el) })
+}
+
 // LoggerTextWriter writes human-readable log records to an io.Writer.
 type LoggerTextWriter struct {
 	LoggerWriter
@@ -25,10 +39,13 @@ type LoggerTextWriter struct {
 	formatter *Formatter
 }
 
+// SetFormatter replaces the formatter used by the text writer.
 func (w *LoggerTextWriter) SetFormatter(formatter *Formatter) *LoggerTextWriter {
 	w.formatter = formatter
 	return w
 }
+
+// Formatter returns the effective formatter for the text writer.
 func (w *LoggerTextWriter) Formatter() *Formatter {
 	if w.formatter == nil {
 		return DefaultTextFormatter
@@ -43,13 +60,7 @@ func (w *LoggerTextWriter) Write(p []byte) (n int, err error) {
 
 // Print formats the provided record as text and writes it to the underlying writer.
 func (w *LoggerTextWriter) Print(level LogLevel, prefix string, traceback []*MethodTraceback, messages ...any) error {
-	msg := Map(messages, func(el any) string { return fmt.Sprint(el) })
-	newline := false
-	if len(msg) > 0 && strings.HasSuffix(msg[len(msg)-1], "\n") {
-		newline = true
-		msg[len(msg)-1] = strings.TrimSuffix(msg[len(msg)-1], "\n")
-	}
-	messages = Map(msg, func(el string) any { return any(el) })
+	newline, messages := PrepareMessages(messages...)
 
 	f := w.Formatter()
 	s := f.FormatMessage(level, prefix, traceback, messages...)
@@ -88,12 +99,15 @@ type LoggerJsonWriter struct {
 	formatter *Formatter
 }
 
+// Formatter returns the effective formatter for the JSON writer.
 func (w *LoggerJsonWriter) Formatter() *Formatter {
 	if w.formatter == nil {
 		return DefaultJsonFormatter
 	}
 	return w.formatter
 }
+
+// SetFormatter replaces the formatter used by the JSON writer.
 func (w *LoggerJsonWriter) SetFormatter(f *Formatter) *LoggerJsonWriter {
 	w.formatter = f
 	return w
@@ -116,13 +130,7 @@ func (w *LoggerJsonWriter) Write(data []byte) (int, error) {
 
 // Print encodes the provided record as JSON and writes it to the underlying writer.
 func (w *LoggerJsonWriter) Print(level LogLevel, prefix string, traceback []*MethodTraceback, messages ...any) error {
-	msg := Map(messages, func(el any) string { return fmt.Sprint(el) })
-	newline := false
-	if len(msg) > 0 && strings.HasSuffix(msg[len(msg)-1], "\n") {
-		newline = true
-		msg[len(msg)-1] = strings.TrimSuffix(msg[len(msg)-1], "\n")
-	}
-	messages = Map(msg, func(el string) any { return any(el) })
+	newline, messages := PrepareMessages(messages...)
 
 	f := w.Formatter()
 	s := f.FormatMessage(level, prefix, traceback, messages...)