yap-6.3/Logtalk/examples/NOTES.txt

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Logtalk - Open source object-oriented logic programming language
Release 2.30.2

Copyright (c) 1998-2007 Paulo Moura.  All Rights Reserved.
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This folder contains several examples of Logtalk programs. A brief 
description of each example is included below.

Each example folder contains a "NOTES.txt" file and a loader helper 
file that may be used to load all the example entities. In addition, 
most examples contain a "SCRIPT.txt" file with instructions on how to 
load the example and sample queries for your to try.

Most of these examples need objects, protocols, and categories that 
are defined in the Logtalk standard library or in other examples. See 
the "NOTES.txt" files inside the library folder, plus the "NOTES.txt" 
and "SCRIPT.txt" files inside each example folder.

Some examples may redefine objects already loaded from other examples.
You may want to restart Logtalk after trying each example.

Some of the examples have been adopted from public available Prolog 
code or from known Prolog text books and are copyrighted by the respective 
authors.

These are programming examples, meaning that you should study the source 
files to fully understand them. However, note that some examples purpose 
is to illustrate general principles rather than being adequate, efficient 
solutions for deployment code.

All examples are formatted using four spaces tabs.

By default, compiling an example generates a XML documenting file for 
each compiled entity (object, category, or protocol). See the "xml" 
folder for instructions on how to browse the XML files for on-line 
reading or how to convert the files to a print-ready format such as PDF.


Here is a short description of each included example:

aliases
	example of using the alias/3 predicate directive to provide 
	alternative names to inherited predicates in order to improve 
	readability or to solve multi-inheritance conflicts

assignvars
	example of using assignable variables in the context of parametric 
	objects in order to represent object state

benchmarks
	simple benchmarks for helping measuring performance of Logtalk 
	message sending between Prolog compilers and for comparing 
	performance of message sending calls with predicate calls in 
	plain Prolog

birds
	bird identification expert system
	(example adopted from the Adventure in Prolog Amzi! book)

bottles
	99 bottles of beer on the wall! Sing along!

bricks
	example of representation and handling of relations using events;
	illustrates how to use events to avoid breaking object encapsulation

classvars
	example of implementation of class variables
	(as found in Smalltalk; i.e. shared instance variables)

dcgs
	examples of using DCG rules inside objects and categories

diamonds
	examples of problems and solutions for the "diamond problem"
	(multi-inheritance conflicts and ambiguities)

dynpred
	example of using some of the built-in database handling methods 
	in order to implement dynamic object state

encodings
	very simple example of using the new, experimental encoding/1 
	directive (requires Logtalk to be run with the SWI-Prolog compiler)

engines
	example of category composition (importation of categories by 
	other categories) using car engines

errors
	example showing the Logtalk compiler warning and error reporting
	for common programming errors

hello_world
	the unavoidable "hello world" programming example

hooks
	simple example of using compiler hook objects and predicates

inheritance
	examples of public, protected, and private inheritance using both 
	prototypes and classes/instances

instmethods
	example of instance defined methods; also illustrates the use of 
	"super calls" to call overridden method definitions

lo
	examples adopted from the Francis G. McCabe L&O system

logic
	example of a translator of first-order predicate logic propositions 
	to conjunctive normal form and to clausal form

lpa
	examples adopted from the LPA Prolog++ system

metapredicates
	example of using meta-predicates in Logtalk objects

metainterpreters
	some examples of simple meta-interpreters defined as categories 
	that can be imported by "database" objects

mi
	simple multi-inheritance examples

miscellaneous
	unsorted examples

modules
	simple example of compiling Prolog module files as objects

msglog
	example of using events and monitors for recording, replaying, 
	and printing user messages

operators
	example of using operators local to objects and categories

parametric
	simple example of parametric objects

poem
	examples adopted from the Ben Staveley-Taylor POEM system

points
	example adopted from SICStus Objects documentation; defines 
	a simple class hierarchy of points illustrating how to use 
	categories as object components

polygons
	example of representation and handling of relations using events

profiling
	examples of using of events and monitors to implement profilers

proxies
	example of using parametric object proxies for an efficient 
	representation of objects with read-only state

puzzles
	several examples of logical puzzles

reflection
	example of a simple class-based reflective system

relations
	objects implementing predicates for dealing with relations and 
	constrained relations between objects; used by other examples

roots
	objects, protocols, and categories needed by most of the other 
	examples; illustrates how you can define object creation and 
	abolishing methods, complete with initialization and termination 
	options

searching
	state-space searching framework
	(example adopted from Ivan Bratko's "Prolog Programming for 
	Artificial Intelligence" book)

shapes
	simple geometric shapes implemented as both a prototype hierarchy 
	and a class hierarchy

sicstus
	examples adopted from SICStus Objects documentation

symdiff
	example of using parametric objects to implement symbolic 
	expression differentiation and simplification

tabling
	simple example of using tabling directives within objects

threads
	several simple examples of multi-threading programming
	(requires Logtalk to be run with either YAP or SWI-Prolog)

viewpoints
	example on how to implement property sharing and value sharing 
	with prototypes