reassign values

object/object.go

@@ -26,6 +26,12 @@ const (
 	CLOSURE_OBJ           = "CLOSURE"
 )
 
+// Mutable is the interface for all mutable objects which must implement
+// the Set() method which rebinds its internal value for assignment statements
+type Mutable interface {
+	Set(obj Object)
+}
+
 type Object interface {
 	Type() ObjectType
 	Inspect() string
@@ -47,6 +53,9 @@ func (i *Integer) Type() ObjectType {
 func (i *Integer) Inspect() string {
 	return fmt.Sprintf("%d", i.Value)
 }
+func (i *Integer) Set(obj Object) {
+	i.Value = obj.(*Integer).Value
+}
 
 type Boolean struct {
 	Value bool
@@ -55,10 +64,12 @@ type Boolean struct {
 func (b *Boolean) Type() ObjectType {
 	return BOOLEAN_OBJ
 }
-
 func (b *Boolean) Inspect() string {
 	return fmt.Sprintf("%t", b.Value)
 }
+func (i *Boolean) Set(obj Object) {
+	i.Value = obj.(*Boolean).Value
+}
 
 type Null struct{}
 
@@ -88,10 +99,12 @@ type Error struct {
 func (e *Error) Type() ObjectType {
 	return ERROR_OBJ
 }
-
 func (e *Error) Inspect() string {
 	return "Error: " + e.Message
 }
+func (e *Error) Set(obj Object) {
+	e.Message = obj.(*Error).Message
+}
 
 type Function struct {
 	Parameters []*ast.Identifier
@@ -128,10 +141,12 @@ type String struct {
 func (s *String) Type() ObjectType {
 	return STRING_OBJ
 }
-
 func (s *String) Inspect() string {
 	return s.Value
 }
+func (s *String) Set(obj Object) {
+	s.Value = obj.(*String).Value
+}
 
 type BuiltinFunction func(args ...Object) Object
 
@@ -150,11 +165,10 @@ type Array struct {
 	Elements []Object
 }
 
-func (ao Array) Type() ObjectType {
+func (ao *Array) Type() ObjectType {
 	return ARRAY_OBJ
 }
-
-func (ao Array) Inspect() string {
+func (ao *Array) Inspect() string {
 	var out bytes.Buffer
 
 	elements := []string{}
@@ -168,6 +182,9 @@ func (ao Array) Inspect() string {
 
 	return out.String()
 }
+func (ao *Array) Set(obj Object) {
+	ao.Elements = obj.(*Array).Elements
+}
 
 type HashKey struct {
 	Type  ObjectType
@@ -213,7 +230,6 @@ type Hash struct {
 func (h *Hash) Type() ObjectType {
 	return HASH_OBJ
 }
-
 func (h *Hash) Inspect() string {
 	var out bytes.Buffer
 
@@ -228,6 +244,9 @@ func (h *Hash) Inspect() string {
 
 	return out.String()
 }
+func (h *Hash) Set(obj Object) {
+	h.Pairs = obj.(*Hash).Pairs
+}
 
 func (cf *CompiledFunction) Type() ObjectType {
 	return COMPILED_FUNCTION_OBJ