Support "-" tag.

decode_test.go

diff --git a/decode_test.go b/decode_test.go
index 5e5663b..83532f4 100644
--- a/decode_test.go
+++ b/decode_test.go
@@ -125,6 +125,13 @@
 	// BUG #1133337
 	{"foo: ''", map[string]*string{"foo": new(string)}},
 	{"foo: null", map[string]string{}},
+
+	// Ignored field
+	{"a: 1\nb: 2\n",
+		&struct {
+			A int
+			B int "-"
+		}{1, 0}},
 }
 
 func (s *S) TestUnmarshal(c *C) {

encode_test.go

diff --git a/encode_test.go b/encode_test.go
index f6a0d0f..1d63c02 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -104,6 +104,13 @@
 			u int
 			A int
 		}{0, 1}},
+
+	// Ignored field
+	{"a: 1\n",
+		&struct {
+			A int
+			B int "-"
+		}{1, 2}},
 }
 
 func (s *S) TestMarshal(c *C) {

goyaml.go

diff --git a/goyaml.go b/goyaml.go
index fa288c9..eb2a29f 100644
--- a/goyaml.go
+++ b/goyaml.go
@@ -187,6 +187,9 @@
 		if tag == "" && strings.Index(string(field.Tag), ":") < 0 {
 			tag = string(field.Tag)
 		}
+		if tag == "-" {
+			continue
+		}
 
 		// XXX Drop this after a few releases.
 		if s := strings.Index(tag, "/"); s >= 0 {