add new Printfer interface
This is for convenience. The client can now call
pretty.Pdiff(logger, a, b) rather than looping over the
results of Diff.
diff --git a/diff.go b/diff.go
index fb9580b..910da56 100644
--- a/diff.go
+++ b/diff.go
@@ -8,37 +8,56 @@
type sbuf []string
-func (s *sbuf) Write(b []byte) (int, error) {
- *s = append(*s, string(b))
- return len(b), nil
+func (p *sbuf) Printf(format string, a ...interface{}) {
+ s := fmt.Sprintf(format, a...)
+ *p = append(*p, s)
}
// Diff returns a slice where each element describes
// a difference between a and b.
func Diff(a, b interface{}) (desc []string) {
- Fdiff((*sbuf)(&desc), a, b)
+ Pdiff((*sbuf)(&desc), a, b)
return desc
}
+// wprintfer calls Fprintf on w for each Printf call
+// with a trailing newline.
+type wprintfer struct{ w io.Writer }
+
+func (p *wprintfer) Printf(format string, a ...interface{}) {
+ fmt.Fprintf(p.w, format, a...)
+}
+
// Fdiff writes to w a description of the differences between a and b.
func Fdiff(w io.Writer, a, b interface{}) {
- diffWriter{w: w}.diff(reflect.ValueOf(a), reflect.ValueOf(b))
+ Pdiff(&wprintfer{w}, a, b)
}
-type diffWriter struct {
- w io.Writer
+type Printfer interface {
+ Printf(format string, a ...interface{})
+}
+
+// Pdiff prints to p a description of the differences between a and b.
+// It calls Printf once for each difference, with no trailing newline.
+// The standard library log.Logger is a Printfer.
+func Pdiff(p Printfer, a, b interface{}) {
+ diffPrinter{w: p}.diff(reflect.ValueOf(a), reflect.ValueOf(b))
+}
+
+type diffPrinter struct {
+ w Printfer
l string // label
}
-func (w diffWriter) printf(f string, a ...interface{}) {
+func (w diffPrinter) printf(f string, a ...interface{}) {
var l string
if w.l != "" {
l = w.l + ": "
}
- fmt.Fprintf(w.w, l+f, a...)
+ w.w.Printf(l+f, a...)
}
-func (w diffWriter) diff(av, bv reflect.Value) {
+func (w diffPrinter) diff(av, bv reflect.Value) {
if !av.IsValid() && bv.IsValid() {
w.printf("nil != %# v", formatter{v: bv, quote: true})
return
@@ -136,7 +155,7 @@
}
}
-func (d diffWriter) relabel(name string) (d1 diffWriter) {
+func (d diffPrinter) relabel(name string) (d1 diffPrinter) {
d1 = d
if d.l != "" && name[0] != '[' {
d1.l += "."
diff --git a/diff_test.go b/diff_test.go
index 782858c..64f7e51 100644
--- a/diff_test.go
+++ b/diff_test.go
@@ -1,6 +1,7 @@
package pretty
import (
+ "bytes"
"fmt"
"testing"
"unsafe"
@@ -138,6 +139,15 @@
}
}
+func TestFdiff(t *testing.T) {
+ var buf bytes.Buffer
+ Fdiff(&buf, 0, 1)
+ want := "0 != 1"
+ if got := buf.String(); got != want {
+ t.Errorf("Fdiff(0, 1) = %q want %q", got, want)
+ }
+}
+
func diffdiff(t *testing.T, got, exp []string) {
minus(t, "unexpected:", got, exp)
minus(t, "missing:", exp, got)
