add Printf function

close.go

@@ -2,14 +2,13 @@ package safe
 
 import (
 	"io"
-	"log"
 )
 
 // Close will close any io.Closer object if it's not nil, any error will be only logged.
 func Close(closer io.Closer, scope string) {
 	if !IsNil(closer) {
 		if err := closer.Close(); !IsNil(err) {
-			log.Printf("error on close '%s': %s", scope, err)
+			Printf("error on close '%s': %s", scope, err)
 		}
 	}
 }

close_example_test.go

@@ -1,10 +1,14 @@
 package safe
 
 import (
+	"fmt"
 	"net/http"
 )
 
 func ExampleClose() {
+	Printf = func(format string, v ...interface{}) {
+		fmt.Printf(format, v)
+	}
 	resp, err := http.DefaultClient.Get("http://example.com")
 	if err != nil {
 		panic(err)

close_test.go

@@ -11,6 +11,7 @@ type stub struct {
 }
 
 func TestClose(t *testing.T) {
+	Printf = func(format string, v ...interface{}) {}
 	tests := []struct {
 		name   string
 		closer func() io.Closer

log.go

@@ -0,0 +1,6 @@
+package safe
+
+import "log"
+
+// Printf is the global function, will be called if Close method returns an error.
+var Printf = log.Printf