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This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2023 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

% start by loading the example and necessary library supporting files:

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

% try some simple queries:

| ?- sort(rational)::sort([1/8, 2/7, 6/5, 2/9, 1/3], Sorted).

Sorted = [1/8, 2/9, 2/7, 1/3, 6/5] yes

| ?- sort(colours)::sort([orange, indigo, red, yellow, violet, blue, green], Sorted).

Sorted = [red, orange, yellow, green, blue, indigo, violet] yes

% using the pseudo-object user implies using the Prolog built-in standard % order operators:

| ?- sort(user)::sort([3, 1, 4, 2, 9], Sorted).

Sorted = [1, 2, 3, 4, 9] yes

% some messages testing object parameter passing and using:

| ?- red_circle(3)::color(Color).

Color = red yes

| ?- red_circle(3)::area(Area).

Area = 28.274334 yes

| ?- red_circle(3)::ancestors(As).

As = [circle(3, red), ellipse(3, 3, red)] yes

% show the execution context using a method (context/3) that is defined in the % hierarchy root and specialized (using super calls) in each descendant:

| ?- red_circle(3)::context.

red_circle1 self: red_circle(3) this: red_circle(3) sender: user

circle2 self: red_circle(3) this: circle(3,red) sender: user

ellipse3 self: red_circle(3) this: ellipse(3,3,red) sender: user

yes

% send a conjunction of messages/goals to an object; just some useful syntax sugar % (don't use message broadcasting syntax in order to workaround a XSB parser bug):

| ?- square(2)::side(Side), square(2)::width(Width), square(2)::height(Height), square(2)::area(Area).

Side = 2 Width = 2 Height = 2 Area = 4 yes

% find all messages accepted by an object:

| ?- square(2)::current_predicate(Pred).

Pred = side/1 ; Pred = width/1 ; Pred = height/1 ; Pred = area/1 yes

% find all data on a specific message accepted by an object:

| ?- square(_)::predicate_property(side(_), Prop).

Prop = public ; Prop = static ; Prop = declared_in(square(_133)) ; Prop = defined_in(square(_164)) yes