root/tags/lgt2311/examples/NOTES.txt

================================================================
Logtalk - Open source object-oriented logic programming language
Release 2.31.1

Copyright (c) 1998-2008 Paulo Moura.  All Rights Reserved.
================================================================


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

complements
    example of using a category to explicitly complement an existing 
    object

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

testing
    some examples of writing unit tests

threads
    several simple examples of multi-threading programming, some of 
    them intended only for benchmarking multi-threading Prolog compilers
    (requires Logtalk to be run with either YAP, SWI-Prolog, or XSB)

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