Add BoolFlag for rawdatastore.

service/rawdatastore/types.go

Index: service/rawdatastore/types.go
diff --git a/service/rawdatastore/types.go b/service/rawdatastore/types.go
index 9b426ad3ff4e35db1ba2213610aa9b6c37aae61d..42c127af0c6fcd37ca0e5c3b37ed28016ab8d517 100644
--- a/service/rawdatastore/types.go
+++ b/service/rawdatastore/types.go
@@ -4,6 +4,10 @@
 
 package rawdatastore
 
+import (
+	"fmt"
+)
+
 // ByteString is a short byte slice (up to 1500 bytes) that can be indexed.
 type ByteString []byte
 
@@ -37,3 +41,27 @@ type TransactionOptions struct {
 	// due to a conflicting transaction. If omitted, it defaults to 3.
 	Attempts int
 }
+
+// Toggle is a tri-state boolean (Auto/True/False), which allows structs
+// to control boolean flags for metadata in a non-ambiguous way.

[Vadim Sh., 2015/07/24 18:53:00]

what is Auto? It IS ambiguous, at leas from reading this comment.

[iannucci, 2015/07/24 20:58:10]

Auto means 'use the default in the field tag'. I've updated the docs on GetMeta,
added a test, etc. Is this clearer now?

+type Toggle byte
+
+// These are the allowed values for Toggle. Any other values are invalid.
+const (
+	Auto Toggle = iota
+	On
+	Off
+)
+
+func (b Toggle) String() string {
+	switch b {
+	case Auto:
+		return "Auto"
+	case On:
+		return "On"
+	case Off:
+		return "Off"
+	default:
+		return fmt.Sprintf("UNKNOWN_Toggle(%d)", b)
+	}
+}