Create some subroutines and test

src/game/rule/operation/bool.go

@@ -0,0 +1,36 @@
+package operation
+
+import (
+	"encoding/json"
+	"errors"
+	"local/sandbox/cards/src/entity"
+)
+
+type Bool func(*entity.Game, interface{}) bool
+
+var boolStringified = map[string]Bool{
+	"charge": charge,
+	"deal":   deal,
+	"bet":    bet,
+	"trade":  trade,
+	"end":    end,
+}
+
+func (foo *Bool) UnmarshalJSON(b []byte) error {
+	var s string
+	if err := json.Unmarshal(b, &s); err != nil {
+		return err
+	}
+
+	return foo.FromString(s)
+}
+
+func (foo *Bool) FromString(s string) error {
+	for k, v := range boolStringified {
+		if k == s {
+			*foo = v
+			return nil
+		}
+	}
+	return errors.New("unknown bool method " + s)
+}