feat(variables): implemented a list of strings value type for template variables

gonf/values.go

@@ -3,6 +3,7 @@ package gonf
 import (
 	"fmt"
 	"log/slog"
+	"strings"
 )
 
 type Value interface {
@@ -71,6 +72,21 @@ func (i IntValue) String() string {
 	return string(i.value)
 }
 
+// ----- StringsListValue ------------------------------------------------------
+type StringsListValue struct {
+	value []string
+}
+
+func (s *StringsListValue) Append(v ...string) {
+	s.value = append(s.value, v...)
+}
+func (s StringsListValue) Bytes() []byte {
+	return []byte(s.String())
+}
+func (s StringsListValue) String() string {
+	return strings.Join(s.value, "\n")
+}
+
 // ----- StringValue -----------------------------------------------------------
 type StringValue struct {
 	value string
@@ -83,8 +99,6 @@ func (s StringValue) String() string {
 	return s.value
 }
 
-// TODO lists
-
 // TODO maps
 
 // TODO what else?

gonf/variables.go

@@ -14,6 +14,22 @@ func init() {
 }
 
 // ----- Public ----------------------------------------------------------------
+func AppendVariable(name string, values ...string) *VariablePromise {
+	if v, ok := variables[name]; ok {
+		if l, ok := v.value.(*StringsListValue); ok {
+			l.Append(values...)
+		}
+		return v
+	}
+	v := &VariablePromise{
+		isDefault: false,
+		name:      name,
+		value:     &StringsListValue{values},
+	}
+	variables[name] = v
+	return v
+}
+
 func Default(name string, value string) *VariablePromise {
 	if v, ok := variables[name]; ok {
 		if !v.isDefault {