Implement sort.Interface to required struct slice

aliasdomain.go

@@ -6,6 +6,13 @@ type AliasDomain struct {
 	target string
 }
 
+// AliasDomainSlice attaches the methods of sort.Interface to []*AliasDomain.
+type AliasDomainSlice []*AliasDomain
+
+func (p AliasDomainSlice) Len() int           { return len(p) }
+func (p AliasDomainSlice) Less(i, j int) bool { return p[i].Name() < p[j].Name() }
+func (p AliasDomainSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
+
 // NewAliasDomain creates a new AliasDomain instance.
 func NewAliasDomain(name, target string) (*AliasDomain, error) {
 	if !validAliasDomainName(name) {