Add slog/17.go125-record-source

Author: devlights

examples/slog/17.go125-record-source/Taskfile.yml

@@ -0,0 +1,8 @@
+# https://taskfile.dev
+
+version: '3'
+
+tasks:
+  default:
+    cmds:
+      - go run .

examples/slog/17.go125-record-source/main.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+type (
+	myHandler struct {
+		handler slog.Handler
+	}
+)
+
+func (me *myHandler) Handle(ctx context.Context, r slog.Record) error {
+	var (
+		// Go 1.25 から追加された
+		// REF: https://pkg.go.dev/log/slog@go1.25.1#Record.Source
+		source = r.Source()
+	)
+	if source == nil {
+		return nil
+	}
+
+	var (
+		f   = filepath.Base(source.File) // ファイルパス (そのままだとフルパス)
+		fn  = source.Function            // 関数
+		l   = source.Line                // 行
+		msg = r.Message
+	)
+	fmt.Printf("%s:%s:%d\t%s\n", f, fn, l, msg)
+
+	return nil
+}
+
+func (me *myHandler) Enabled(ctx context.Context, l slog.Level) bool {
+	return me.handler.Enabled(ctx, l)
+}
+
+func (me *myHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return &myHandler{handler: me.handler.WithAttrs(attrs)}
+}
+
+func (me *myHandler) WithGroup(name string) slog.Handler {
+	return &myHandler{handler: me.handler.WithGroup(name)}
+}
+
+func main() {
+	if err := run(); err != nil {
+		slog.Error("failed to run", "error", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	var (
+		v = &slog.LevelVar{}
+		o = &slog.HandlerOptions{
+			Level:     v,
+			AddSource: true,
+		}
+		w = os.Stderr
+		h = &myHandler{handler: slog.NewTextHandler(w, o)}
+		l = slog.New(h)
+	)
+	l.Info("Start")
+	{
+		time.Sleep(1 * time.Second)
+		v.Set(slog.LevelWarn)
+	}
+	l.Info("End")
+
+	return nil
+}