sloglm

t := time.Date(2023, 05, 04, 20, 30, 40, 0, time.UTC)
logger := slog.New(NewHandler(os.Stdout, nil, nil))
logger.Info("A `level` message `at` `about` and `.about.bar`",
	"level", slog.LevelInfo,
	"at", t,
	"level", 7,
	"about", slog.GroupValue(
		slog.Bool("foo", true),
		slog.Int("bar", 4711),
		slog.Float64("baz", 3.14159),
	),
)

Output:

A `level:INFO` message `at:2023-05-04T20:30:40Z` `about:[foo=true bar=4711 baz=3.14159]` and `.about.bar:4711` (level=7)

const form = "added `count` x `item` to shopping cart by `user`"
args := []any{"count", 7, "item", "Hat", "user", "John Doe"}
opts := slog.HandlerOptions{Level: &slog.LevelVar{}, AddSource: true}

logger := slog.New(slog.NewTextHandler(os.Stdout, &opts))
fmt.Println("Std Text:")
logger.Info(form, args...)
logger.WithGroup("gruppe").Info(form, args...)
logger = slog.New(slog.NewJSONHandler(os.Stdout, &opts))
fmt.Println("Std JSON:")
logger.Info(form, args...)
logger.WithGroup("gruppe").Info(form, args...)

logger = slog.New(NewHandler(
	os.Stdout,
	NewHeader(sllm.Tdefault|sllm.Tyear).Append,
	&opts,
))
fmt.Println("sllm:")
logger.Info(form, args...)
logger.WithGroup("gruppe").Info(form, args...)
// DISABLED Output:
// time=2023-05-06T13:24:00.476+02:00 level=INFO msg="added `count` x `item` to shopping cart by `user`" count=7 item=Hat user="John Doe"
// {"time":"2023-05-06T13:24:00.476762195+02:00","level":"INFO","msg":"added `count` x `item` to shopping cart by `user`","count":7,"item":"Hat","user":"John Doe"}
// 2023-05-06 Sa 13:24:00 INFO	added `count:7` x `item:Hat` to shopping cart by `user:John Doe`