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Logtalk - Object oriented extension to Prolog
Release 2.22.1

Copyright (c) 1998-2004 Paulo Moura.  All Rights Reserved.
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% start by loading the necessary library and support example files (if not 
% already loaded):

| ?- logtalk_load([library(events_loader), library(types_loader), library(metapredicates_loader), library(hierarchies_loader)]).
...

| ?- logtalk_load(roots(loader)).
...

| ?- logtalk_load(relations(loader)).
...


% now you are ready for loading the example:

| ?- logtalk_load(points(loader)).
...


% let's start with a simple point:

| ?- point::new(Point,[position-(1, 3)]), Point::(print, move(7, 4), print).

p1 @ (1, 3)
p1 @ (7, 4)

Point = p1 ? 

yes


% same problem but with bounds on coordinate values:

| ?- bounded_point::new(Point,[position-(1, 3), bounds(x)-(0, 13), bounds(y)-(-7, 7)]), Point::(print, move(7, 4), print).

bounds(x) : 0,13
bounds(y) : -7,7
bp2 @ (1, 3)
bounds(x) : 0,13
bounds(y) : -7,7
bp2 @ (7, 4)

Point = bp2 ? 

yes


% same problem but storing the history of coordinate values:

| ?- history_point::new(Point,[position-(1, 3)]), Point::(print, move(7, 4), print).

location history: []
hp3 @ (1, 3)
location history: [(1,3)]
hp3 @ (7, 4)

Point = hp3 ? 

yes


% same problem but with bounds on coordinate values and storing past values:

| ?- bounded_history_point::new(Point,[position-(1, 3), bounds(x)-(0, 13), bounds(y)-(-7, 7)]), Point::(print, move(7, 4), print).

bounds(x) : 0,13
bounds(y) : -7,7
location history: []
bhp4 @ (1, 3)
bounds(x) : 0,13
bounds(y) : -7,7
location history: [(1,3)]
bhp4 @ (7, 4)

Point = bhp4 ? 

yes


% clean up instances:

| ?- (point, bounded_point, history_point, bounded_history_point)::delete_all.
yes