minor improvement

color.go

@@ -82,7 +82,7 @@ func WriteRich(w io.Writer, s string, colorCode int, options ...RichOption) {
 		for _, output := range p.outputs {
 			if SupportColors(output) {
 				if len(richBytes) == 0 {
-					richBytes = []byte(Rich(s, colorCode, options...))
+					richBytes = []byte(Rich(s, colorCode, options...)) // no strToBytes; colors are conflicting with --race detector.
 				}
 
 				_, _ = output.Write(richBytes)

printer.go

@@ -42,7 +42,7 @@ type Printer struct {
 	// and write raw text to those that do not (e.g. files).
 	// Note: we could implementing our own multi writer and skip the use
 	// of the std package, but let's don't do that unless is requested.
-	outputs []io.Writer
+	outputs []*outputWriter
 
 	mu       sync.Mutex
 	marshal  MarshalerFunc
@@ -102,7 +102,7 @@ func NewPrinter(name string, output io.Writer) *Printer {
 	p := &Printer{
 		Name:       name,
 		Output:     output,
-		outputs:    []io.Writer{output},
+		outputs:    wrapWriters(output),
 		Writer:     buf,
 		Reader:     buf,
 		Closer:     NopCloser(),
@@ -247,7 +247,7 @@ func (p *Printer) AddOutput(writers ...io.Writer) *Printer {
 		}
 	}
 
-	p.outputs = append(p.outputs, writers...)
+	p.outputs = append(p.outputs, wrapWriters(writers...)...)
 
 	w := io.MultiWriter(append(writers, p.Output)...)
 
@@ -287,7 +287,7 @@ func (p *Printer) SetOutput(writers ...io.Writer) *Printer {
 	}
 
 	p.mu.Lock()
-	p.outputs = writers
+	p.outputs = wrapWriters(writers...)
 	p.Output = w
 	p.IsTerminal = terminal.IsTerminal(w)
 	p.mu.Unlock()

terminal.go

@@ -7,8 +7,35 @@ import (
 	"github.com/kataras/pio/terminal"
 )
 
+// outputWriter just caches the "supportColors"
+// in order to reduce syscalls for known printers.
+type outputWriter struct {
+	io.Writer
+	supportColors bool
+}
+
+func wrapWriters(output ...io.Writer) []*outputWriter {
+	outs := make([]*outputWriter, 0, len(output))
+	for _, w := range output {
+		outs = append(outs, &outputWriter{
+			Writer:        w,
+			supportColors: SupportColors(w),
+		})
+	}
+
+	return outs
+}
+
 // SupportColors reports whether the "w" io.Writer is not a file and it does support colors.
 func SupportColors(w io.Writer) bool {
+	if w == nil {
+		return false
+	}
+
+	if sc, ok := w.(*outputWriter); ok {
+		return sc.supportColors
+	}
+
 	isTerminal := !IsNop(w) && terminal.IsTerminal(w)
 	if isTerminal && runtime.GOOS == "windows" {
 		// if on windows then return true only when it does support 256-bit colors,