From ddd26259b251ecd9d71d4fcc41fa37099c28ad68 Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Fri, 25 Jan 2019 17:32:53 -0500
Subject: [PATCH] merr: make New take in optional key/value pairs for
 convenience

---
 merr/kv_test.go | 14 +++++++++-----
 merr/merr.go    | 26 +++++++++++++++++++-------
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/merr/kv_test.go b/merr/kv_test.go
index 28a8b9b..dc1f107 100644
--- a/merr/kv_test.go
+++ b/merr/kv_test.go
@@ -15,12 +15,13 @@ func TestKV(t *T) {
 		massert.Len(KV(nil).KV(), 0),
 	))
 
-	er := New("foo")
+	er := New("foo", "bar", "baz")
 	kv := KV(er).KV()
 	massert.Fatal(t, massert.Comment(
 		massert.All(
-			massert.Len(kv, 2),
+			massert.Len(kv, 3),
 			massert.Equal("foo", kv["err"]),
+			massert.Equal("baz", kv["bar"]),
 			massert.Equal(true,
 				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
 		),
@@ -36,8 +37,9 @@ func TestKV(t *T) {
 	kv = KV(er).KV()
 	massert.Fatal(t, massert.Comment(
 		massert.All(
-			massert.Len(kv, 3),
+			massert.Len(kv, 4),
 			massert.Equal("foo", kv["err"]),
+			massert.Equal("baz", kv["bar"]),
 			massert.Equal(true,
 				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
 			massert.Equal("1", kv["k"]),
@@ -49,8 +51,9 @@ func TestKV(t *T) {
 	kv = KV(er).KV()
 	massert.Fatal(t, massert.Comment(
 		massert.All(
-			massert.Len(kv, 4),
+			massert.Len(kv, 5),
 			massert.Equal("foo", kv["err"]),
+			massert.Equal("baz", kv["bar"]),
 			massert.Equal(true,
 				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
 			massert.Equal("1", kv["merr.A(k)"]),
@@ -63,8 +66,9 @@ func TestKV(t *T) {
 	kv = KV(er).KV()
 	massert.Fatal(t, massert.Comment(
 		massert.All(
-			massert.Len(kv, 5),
+			massert.Len(kv, 6),
 			massert.Equal("foo", kv["err"]),
+			massert.Equal("baz", kv["bar"]),
 			massert.Equal(true,
 				strings.HasPrefix(kv["errSrc"].(string), "merr/kv_test.go:")),
 			massert.Equal("1", kv["merr.A(k)"]),
diff --git a/merr/merr.go b/merr/merr.go
index f162501..f585e21 100644
--- a/merr/merr.go
+++ b/merr/merr.go
@@ -83,13 +83,25 @@ func Wrap(e error) error {
 // New returns a new error with the given string as its error string. New
 // automatically wraps the error in merr's inner type, which embeds information
 // like the stack trace.
-func New(str string) error {
-	return wrap(errors.New(str), false, 1)
-}
-
-// Errorf is like New, but allows for formatting of the string.
-func Errorf(str string, args ...interface{}) error {
-	return wrap(fmt.Errorf(str, args...), false, 1)
+//
+// For convenience, visible key/values may be passed into New at this point. For
+// example, the following two are equivalent:
+//
+//	merr.WithValue(merr.New("foo"), "bar", "baz", true)
+//	merr.New("foo", "bar", "baz")
+//
+func New(str string, kvs ...interface{}) error {
+	if len(kvs)%2 != 0 {
+		panic("key passed in without corresponding value")
+	}
+	err := wrap(errors.New(str), false, 1)
+	for i := 0; i < len(kvs); i += 2 {
+		err.attr[kvs[i]] = val{
+			visible: true,
+			val:     kvs[i+1],
+		}
+	}
+	return err
 }
 
 func (er *err) visibleAttrs() [][2]string {