From ec9861d23be27058a7ff0859cbf8badac6d7b978 Mon Sep 17 00:00:00 2001
From: LeonardoBizzoni <leo2002714@gmail.com>
Date: Sun, 24 Dec 2023 12:10:40 +0100
Subject: [PATCH] Fixato cancellazione definizione di `this`

---
 Prolog/README.org | 58 ++++++++++++++++++++++++++++++-----------------
 Prolog/oop.pl     | 22 +++++++++++-------
 2 files changed, 51 insertions(+), 29 deletions(-)

diff --git a/Prolog/README.org b/Prolog/README.org
index b23a6f2..5facf4d 100644
--- a/Prolog/README.org
+++ b/Prolog/README.org
@@ -1,5 +1,8 @@
 #+title: 💀 OOΠ in Prolog 💀
-#+author: Bizzoni Leonardo (899629), Barone Matteo(894594), Kier Mirko Tolentino(899728)
+#+author: Bizzoni Leonardo (899629),
+#+author: Barone Matteo(894594),
+#+author: Kier Mirko Tolentino(899728)
+#+options: TOC:nil
 
 * Breve descrizione
 42
@@ -60,18 +63,22 @@ def_class(ClassName, Parents, Parts) :-
 *** Esempio pratico
 #+name: def_class
 #+begin_src prolog
-def_class(foo, [], [field(foo, 42), method(foo, [Number], (field(this, foo, Foo),
-							     Sum is Number + Foo,
-							     write("Sum: "), writeln(Sum)))]).
-
-def_class(bar, [], [field(bar, "42"), method(bar, [], (write("Favorite number is "),
-							 field(this, bar, Bar),
-							 writeln(Bar)))]).
-
-def_class(foobar, [foo, bar], [field(foobar, "Baz"), method(foobar, [X, X, [X]], (!)), method(foobar, [Start, End, [Start | Ls]], (Start =< End,
-																     N is Start + 1,
-																     foobar(this, N, End, Ls)))]).
-
+def_class(foo, [], [field(foo, 42),
+		    method(foo, [Number], (field(this, foo, Foo),
+					   Sum is Number + Foo,
+					   write("Sum: "), writeln(Sum)))]).
+
+def_class(bar, [], [field(bar, "42"),
+		    method(bar, [], (write("Favorite number is "),
+				     field(this, bar, Bar),
+				     writeln(Bar)))]).
+
+def_class(foobar, [foo, bar], [field(foobar, "Baz"),
+			       method(foobar, [X, X, [X]], (!)),
+			       method(foobar, [Start, End, [Start | Ls]],
+				      (Start =< End,
+				       N is Start + 1,
+				       foobar(this, N, End, Ls)))]).
 #+end_src
 ** make
 *** Definizione
@@ -165,7 +172,7 @@ fieldx(Instance, [FieldName], Res) :-
     !.
 fieldx(Instance, [FieldName | Others], Res) :-
     is_instance(Instance),
-    field(Instance, FieldName, Value),
+    field(Instance, FieldName, _Value),
     fieldx(Instance, Others, Res).
 #+end_src
 
@@ -288,16 +295,25 @@ check_fields(InstanceName, [=(Field, Value) | Other]) :-
 
 ** define_this
 #+begin_src prolog :tangle oop.pl
-define_this(Instance) :-
+define_this(Instance, For) :-
     \+ is_list(Instance),
     !,
     findall(Key = Value, field(Instance, Key, Value), List),
-    define_this(List).
+    define_this(List, For).
 
-define_this([]) :- !.
-define_this([=(Key, Value) | Other]) :-
+define_this([], []) :- !.
+define_this([=(Key, Value) | Other], [Key | Rest]) :-
     asserta(field(this, Key, Value)),
-    define_this(Other).
+    define_this(Other, Rest).
+#+end_src
+
+** undefine_this
+#+begin_src prolog :tangle oop.pl
+undefine_this([]) :- !.
+undefine_this([FieldName | Other]) :-
+    retract(field(this, FieldName, _Value)),
+    !,
+    undefine_this(Other).
 #+end_src
 
 ** call_method
@@ -305,10 +321,10 @@ define_this([=(Key, Value) | Other]) :-
 call_method(Instance, ClassName, Body) :-
     is_instance(Instance, ClassName),
     asserta(is_instance(this, ClassName)),
-    define_this(Instance),
+    define_this(Instance, For),
     call_cleanup(call(Body), (
 		     retractall(is_instance(this, ClassName)),
-		     retractall(field(this, _, _)))).
+		     undefine_this(For))).
 #+end_src
 
 ** check_value_type
diff --git a/Prolog/oop.pl b/Prolog/oop.pl
index 3ec30c9..9b2c415 100644
--- a/Prolog/oop.pl
+++ b/Prolog/oop.pl
@@ -95,7 +95,7 @@ fieldx(Instance, [FieldName], Res) :-
     !.
 fieldx(Instance, [FieldName | Others], Res) :-
     is_instance(Instance),
-    field(Instance, FieldName, Value),
+    field(Instance, FieldName, _Value),
     fieldx(Instance, Others, Res).
 
 :- dynamic is_class/1.
@@ -194,24 +194,30 @@ check_fields(InstanceName, [=(Field, Value) | Other]) :-
     field(InstanceName, Field, Value),
     check_fields(InstanceName, Other).
 
-define_this(Instance) :-
+define_this(Instance, For) :-
     \+ is_list(Instance),
     !,
     findall(Key = Value, field(Instance, Key, Value), List),
-    define_this(List).
+    define_this(List, For).
 
-define_this([]) :- !.
-define_this([=(Key, Value) | Other]) :-
+define_this([], []) :- !.
+define_this([=(Key, Value) | Other], [Key | Rest]) :-
     asserta(field(this, Key, Value)),
-    define_this(Other).
+    define_this(Other, Rest).
+
+undefine_this([]) :- !.
+undefine_this([FieldName | Other]) :-
+    retract(field(this, FieldName, _Value)),
+    !,
+    undefine_this(Other).
 
 call_method(Instance, ClassName, Body) :-
     is_instance(Instance, ClassName),
     asserta(is_instance(this, ClassName)),
-    define_this(Instance),
+    define_this(Instance, For),
     call_cleanup(call(Body), (
 		     retractall(is_instance(this, ClassName)),
-		     retractall(field(this, _, _)))).
+		     undefine_this(For))).
 
 check_value_type(nil, _X) :- !.
 check_value_type(var, X) :- var(X), !.
-- 
2.52.0