1 files changed, 48 insertions, 0 deletions
diff --git a/slog/example_wrap_test.go b/slog/example_wrap_test.go
new file mode 100644
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+++ b/slog/example_wrap_test.go
@@ -0,0 +1,48 @@
+// 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"
+	"os"
+	"path/filepath"
+	"runtime"
+	"time"
+
+	"golang.org/x/exp/slog"
+)
+
+// 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:44 msg="message, formatted"
+}