sample how to combine SetLogTracer and flag.Parse to have runtime flags

Author: lainio

samples/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"log"
+	"os"
 
 	"github.com/lainio/err2"
 )
@@ -12,6 +13,11 @@ var (
 	isErr = flag.Bool("err", false, "tells if we want to have an error")
 )
 
+func init() {
+	// highlight that this is before flag.Parse to allow it to work properly.
+	err2.SetLogTracer(os.Stderr)
+}
+
 func main() {
 	defer err2.Catch(err2.Stderr)
 	log.SetFlags(log.Lshortfile | log.LstdFlags)