add new Logfer interface This is for convenience. The client can now call pretty.Ldiff(t, a, b) in tests rather than looping over the results of Diff.

diff --git a/diff.go b/diff.go
index 6df2f86..b08522d 100644
--- a/diff.go
+++ b/diff.go

@@ -44,6 +44,25 @@
 	diffPrinter{w: p}.diff(reflect.ValueOf(a), reflect.ValueOf(b))
 }
 
+type Logfer interface {
+	Logf(format string, a ...interface{})
+}
+
+// logprintfer calls Fprintf on w for each Printf call
+// with a trailing newline.
+type logprintfer struct{ l Logfer }
+
+func (p *logprintfer) Printf(format string, a ...interface{}) {
+	p.l.Logf(format, a...)
+}
+
+// Ldiff prints to l a description of the differences between a and b.
+// It calls Logf once for each difference, with no trailing newline.
+// The standard library testing.T and testing.B are Logfers.
+func Ldiff(l Logfer, a, b interface{}) {
+	Pdiff(&logprintfer{l}, a, b)
+}
+
 type diffPrinter struct {
 	w Printfer
 	l string // label

diff --git a/diff_test.go b/diff_test.go
index eab6c47..c47c9f0 100644
--- a/diff_test.go
+++ b/diff_test.go

@@ -3,10 +3,17 @@
 import (
 	"bytes"
 	"fmt"
+	"log"
 	"testing"
 	"unsafe"
 )
 
+var (
+	_ Logfer   = (*testing.T)(nil)
+	_ Logfer   = (*testing.B)(nil)
+	_ Printfer = (*log.Logger)(nil)
+)
+
 type difftest struct {
 	a   interface{}
 	b   interface{}