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// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package slog_test
import (
"context"
"fmt"
"log/slog"
"os"
"path/filepath"
"runtime"
"time"
)
// Infof is an example of a user-defined logging function that wraps slog.
// The log record contains the source position of the caller of Infof.
func Infof(logger *slog.Logger, format string, args ...any) {
if !logger.Enabled(context.Background(), slog.LevelInfo) {
return
}
var pcs [1]uintptr
runtime.Callers(2, pcs[:]) // skip [Callers, Infof]
r := slog.NewRecord(time.Now(), slog.LevelInfo, fmt.Sprintf(format, args...), pcs[0])
_ = logger.Handler().Handle(context.Background(), r)
}
func Example_wrapping() {
replace := func(groups []string, a slog.Attr) slog.Attr {
// Remove time.
if a.Key == slog.TimeKey && len(groups) == 0 {
return slog.Attr{}
}
// Remove the directory from the source's filename.
if a.Key == slog.SourceKey {
source := a.Value.Any().(*slog.Source)
source.File = filepath.Base(source.File)
}
return a
}
logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{AddSource: true, ReplaceAttr: replace}))
Infof(logger, "message, %s", "formatted")
// Output:
// level=INFO source=example_wrap_test.go:43 msg="message, formatted"
}
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