feat: create log package.

log/logger.go

@@ -0,0 +1,59 @@
+package log
+
+import (
+	"log"
+	"os"
+)
+
+// Logger is an optional custom logger.
+var Logger *log.Logger
+
+// Fatal writes a log entry.
+// It uses Logger if not nil, otherwise it uses the default log.Logger.
+func Fatal(args ...interface{}) {
+	if Logger == nil {
+		Logger = log.New(os.Stderr, "", log.LstdFlags)
+	}
+
+	Logger.Fatal(args...)
+}
+
+// Fatalf writes a log entry.
+// It uses Logger if not nil, otherwise it uses the default log.Logger.
+func Fatalf(format string, args ...interface{}) {
+	if Logger == nil {
+		Logger = log.New(os.Stderr, "", log.LstdFlags)
+	}
+
+	Logger.Fatalf(format, args...)
+}
+
+// Print writes a log entry.
+// It uses Logger if not nil, otherwise it uses the default log.Logger.
+func Print(args ...interface{}) {
+	if Logger == nil {
+		Logger = log.New(os.Stdout, "", log.LstdFlags)
+	}
+
+	Logger.Print(args...)
+}
+
+// Println writes a log entry.
+// It uses Logger if not nil, otherwise it uses the default log.Logger.
+func Println(args ...interface{}) {
+	if Logger == nil {
+		Logger = log.New(os.Stdout, "", log.LstdFlags)
+	}
+
+	Logger.Println(args...)
+}
+
+// Printf writes a log entry.
+// It uses Logger if not nil, otherwise it uses the default log.Logger.
+func Printf(format string, args ...interface{}) {
+	if Logger == nil {
+		Logger = log.New(os.Stdout, "", log.LstdFlags)
+	}
+
+	Logger.Printf(format, args...)
+}