1// Copyright 2022 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package slog_test 6 7import ( 8 "context" 9 "fmt" 10 "log/slog" 11 "os" 12 "path/filepath" 13 "runtime" 14 "time" 15) 16 17// Infof is an example of a user-defined logging function that wraps slog. 18// The log record contains the source position of the caller of Infof. 19func Infof(logger *slog.Logger, format string, args ...any) { 20 if !logger.Enabled(context.Background(), slog.LevelInfo) { 21 return 22 } 23 var pcs [1]uintptr 24 runtime.Callers(2, pcs[:]) // skip [Callers, Infof] 25 r := slog.NewRecord(time.Now(), slog.LevelInfo, fmt.Sprintf(format, args...), pcs[0]) 26 _ = logger.Handler().Handle(context.Background(), r) 27} 28 29func Example_wrapping() { 30 replace := func(groups []string, a slog.Attr) slog.Attr { 31 // Remove time. 32 if a.Key == slog.TimeKey && len(groups) == 0 { 33 return slog.Attr{} 34 } 35 // Remove the directory from the source's filename. 36 if a.Key == slog.SourceKey { 37 source := a.Value.Any().(*slog.Source) 38 source.File = filepath.Base(source.File) 39 } 40 return a 41 } 42 logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{AddSource: true, ReplaceAttr: replace})) 43 Infof(logger, "message, %s", "formatted") 44 45 // Output: 46 // level=INFO source=example_wrap_test.go:43 msg="message, formatted" 47} 48