add bracket format (#15)

Reviewed-on: #15
Co-authored-by: andrey <andrey@4devs.io>
Co-committed-by: andrey <andrey@4devs.io>

writer_example_test.go

@@ -0,0 +1,37 @@
+package log_test
+
+import (
+	"context"
+	"math"
+	"path/filepath"
+	"time"
+
+	"gitoa.ru/go-4devs/log"
+	"gitoa.ru/go-4devs/log/entry"
+	"gitoa.ru/go-4devs/log/field"
+	"gitoa.ru/go-4devs/log/level"
+)
+
+func exampleWithTime(key, format string) log.Middleware {
+	return func(ctx context.Context, e *entry.Entry, handler log.Logger) (int, error) {
+		return handler(ctx, e.Add(field.FormatTime(key, format, time.Unix(math.MaxInt32, 0).In(time.UTC))))
+	}
+}
+
+func ExampleFormatWithBracket() {
+	ctx := context.Background()
+	logger := log.New(log.WithFormat(log.FormatWithBracket()), log.WithStdout()).With(
+		log.WithSource(10, filepath.Base),
+		// log.WithTime(log.KeyTime, time.RFC3339),
+		exampleWithTime(log.KeyTime, time.RFC3339),
+		log.WithLevel(log.KeyLevel, level.Info),
+	)
+
+	logger.InfoKV(ctx, "imfo message", field.Int64("num", 42))
+
+	serviceLogger := logger.With(log.WithName("service_name"))
+	serviceLogger.Err(ctx, "error message")
+	// Output:
+	// 2038-01-19T03:14:07Z [info] writer_example_test.go:30 "imfo message" num=42
+	// 2038-01-19T03:14:07Z [error][service_name] writer_example_test.go:33 "error message"
+}