Adding string pointer. (#380)

ptr/ptr.go

@@ -27,3 +27,9 @@ func Int64(i int64) *int64 {
 func Bool(b bool) *bool {
 	return &b
 }
+
+// String is a helper for turning strings into pointers for use in
+// API types that want *string.
+func String(s string) *string {
+	return &s
+}

ptr/ptr_test.go

@@ -33,3 +33,11 @@ func TestBool(t *testing.T) {
 		t.Errorf("Bool() = &%v, wanted %v", *gotPtr, want)
 	}
 }
+
+func TestString(t *testing.T) {
+	want := "should be a pointer"
+	gotPtr := String(want)
+	if want != *gotPtr {
+		t.Errorf("String() = &%v, wanted %v", *gotPtr, want)
+	}
+}