root/tags/lgt2310/RELEASE_NOTES.txt

================================================================
Logtalk - Open source object-oriented logic programming language
Release 2.31.0

Copyright (c) 1998-2007 Paulo Moura.  All Rights Reserved.
================================================================


RELEASE NOTES
=============


2.31.0 - December 21, 2007

    Added a new built-in protocol, "expanding", declaring goal_expansion/2
    and term_expansion/2 public predicates.

    Added compiler support for user-defined goal expansion hooks. Changed 
    the implementation of compiler term and goal expansion hooks to use 
    object-defined predicates term_expansion/2 and goal_expansion/2.
    Changed the compiler option "hook" to accept object identifiers.

    Allow a category to explicitly complement an existing object, thus 
    providing functionality similar to Objective-C categories. Added 
    complements_object/2 built-in predicate. Added a new example, 
    "complements", illustrating the new category functionality.

    When constructing a new category from other categories, the relation 
    "extends" is now used instead of the relation "imports". The relation 
    "imports" is now only used when an object imports a category. Added  
    extends_category/2-3 built-in predicates.

    Modified the built-in predicate define_events/5 to throw an existence 
    error instead of failing when the specified monitor object does not 
    exists. 

    Updated the Logtalk compiler to convert version numbers to atoms when 
    generating XML documenting files (thus avoiding problems with some 
    Prolog compilers that resulted in version numbers with a large number 
    of fractional digits).

    Improved updating of runtime bookkeeping tables when loading source 
    files.

    Renamed the predicate property "alias/1" to "alias_of/1" in order to 
    disambiguate its meaning.

    Added a new config file, "k6.config", for the K-Prolog 6.0 beta 
    version.

    Updated the B-Prolog config file to recognize mode/1 directives.
    Added some missing meta-predicate specifications to the config files 
    of XSB and YAP.

    Updated the Windows GUI installer to support running Logtalk with 
    CxProlog 0.96.1 and later versions.

    Added two new multi-threading examples, "fibonacci" and "hanoi", and 
    corrected a bug in the recursive creation of threads on the "sorting" 
    example. Updated the "primes" multi-threading example to also support 
    eight threads.

    Updated the "hooks" example for illustrating goal expansion hooks in 
    addition to term expansion hooks.

    Updated the "engines" example for compliance with the changes made 
    to category relations.

    Added syntax coloring support for the new goal_expansion/1, 
    complements_object/2, and extends_category/2-3 predicates to all 
    supported text editors.

    Updated the TextMate code snippets to use the TM_FULLNAME variable 
    instead of the deprecated "niutil" command to retrieve the user full 
    name. Thanks to Michael Sheets for the update. 


2.30.8 - November 9, 2007

    Fixed bug in the compilation of synchronized predicates that breaks 
    Logtalk on single-threaded Prolog compilers.


2.30.7 - November 5, 2007

    Updated the multi-threading built-in predicates threaded_notify/1 and 
    threaded_wait/1 to accept lists of notifications.

    Added a new read-only compiler flag, "context_switching_calls", allowing 
    context switching calls to be disabled (they are enabled by default).

    Updated the B-Prolog config file to recognize eager_consume/1 directives.
    Updated the XSB config file to recognize use_subsumptive_tabling/1,
    use_variant_tabling/1, index/1, thread_private/1, and thread_shared/1 
    directives.
    Updated the YAP config file to recognize thread_local/1 directives.
    Updated the SICStus Prolog config files to recognize volatile/1 directives.
    Updated the SWI-Prolog config file to recognize thread_local/1, index/1, 
    and hash/1 directives.

    Changed the backup directory names generated by the "cplgtdirs.*" shell 
    scripts to not include whitespace characters.

    Updated the "xsbmtlgt.sh" integration script to start XSB-MT using the 
    new command-line option "--shared_predicates" (requires current XSB CVS 
    version). Updated the Windows GUI installer to support running Logtalk 
    with XSB-MT.

    Added a multi-threading example, "barriers", of barrier synchronization.

    Updated the "functions" example sample queries for compatibility with the 
    ISO Prolog standard regarding representation of float numbers.

    Added a workaround for a parsing bug in XSB while compiling the "sicstus" 
    example.


2.30.6 - October 21, 2007

    Replaced calls to the proprietary current_thread/2 predicate in the 
    Logtalk runtime by calls to the thread_property/2 predicate as per 
    the ISO DTR on multi-threading predicates. Added a goal_expansion/2 
    clause to the SWI-Prolog config file to automatically switch between 
    the current_thread/2 and thread_property/2 predicates depending on 
    availability.

    Changed handling of the encoding/1 directive by the Logtalk compiler in 
    order to improve compatibility with YAP and SICStus Prolog. Removed from 
    the config files the now obsolete '$lgt_set_stream_encoding'/2 predicate 
    definition. Renamed the compiler option "supports_encoding_dir" to 
    "encoding_directive" and changed its possible values to "unsupported", 
    "full" (used in both Logtalk source files and compiler generated Prolog 
    files), and "source" (used only in Logtalk source files).

    Renamed compiler option "underscore_vars" to "underscore_variables".
    Renamed compiler option "supports_break_predicate" to "break_predicate".

    Improved the performance of recursive predicate definitions synchronized 
    by mutexes. Explicitly create all mutexes used by an entity at load time 
    for compatibility with XSB. Several changes to multi-threading support in 
    order to improve compatibility with current and forthcoming versions of 
    YAP, SWI-Prolog, and XSB.

    Updated the Logtalk compiler for compatibility with both logical and 
    immediate update semantics when compiling synchronized predicates.

    Updated the meta-predicate compilation sanity checks to verify the 
    existence of the minimum number of normal arguments in a clause head 
    required by the closure of maximum arity.

    Added a workaround for the lack of built-in support for character 
    unbuffered input when using the Logtalk built-in debugger to the config 
    files of ALS Prolog, B-Prolog, Ciao, CxProlog, IF/Prolog, JIProlog, 
    Prolog II+, SICStus Prolog, XSB, and YAP. Thanks to Parker Jones for the 
    bug report.

    Updated the YAP config file to auto-detect working Unicode support when 
    setting the "encoding_directive" compiler option.

    Updated the XSB config file to auto-detect multi-threading support
    when setting the "threads" compiler option. Added an integration script 
    (xsbmtlgt.sh) and supporting files for the multi-threaded version of XSB 
    (requires current development version, available from the XSB CVS server).

    Added a MacPorts portfile for building MacOS X installer packages.

    Added a BOM to the "babel.lgt" UTF-8 file in the "encodings" example in 
    order to improve compatibility with SICStus Prolog.

    Updated the library object "random" by replacing the synchronized/0 
    directive by a synchronized/1 directive listing only the predicates 
    that modify the random number seed.

    Added syntax coloring support for the GtkSourceView 2.x text widget 
    (used e.g. on the Gnome's Gedit text editor and on the MonoDevelop IDE).
    Removed syntax coloring for the obsolete atomic/1 predicate directive 
    from the support files of Source-highlight, Emacs, SubEthaEdit, jEdit, 
    and Kate. Optimized the regular expressions used in most syntax coloring 
    configuration files of supported text editors.


2.30.5 - September 19, 2007

    Added new multi-threading built-in predicates threaded_call/2, 
    threaded_once/2, threaded_exit/2, and threaded_peek/2. These new 
    predicates support the use of threaded call identifier tags in order to 
    link specific threaded_call/2 and threaded_once/2 calls to specific 
    threaded_exit/2 and threaded_peek/2 calls. Extended the "nondet" example 
    in order to illustrate the new functionality.

    Changed the implementation of the built-in predicate threaded_exit/1 in 
    order to avoid blocking when its argument is subsumed by the argument of 
    the corresponding threaded_call/1 call instead of being a variant.

    Updated the Logtalk compiler to encapsulate resource errors inside 
    error/2 exception terms (as specified in the ISO Prolog core standard).

    Corrected a bug in the library object "lgtunit" (wrong arity on two 
    failed_test/2 predicate calls).

    Corrected two problems with the "testing" example: a wrong call on the 
    object "dyn_tests" and a missing entry in the "libpaths.pl" file. Removed 
    two pointless dynamic predicate directives in the "buffer" example.

    Improved documentation of multi-threading programming and predicate 
    properties. Corrected the reference manual page describing the threaded/0 
    directive.

    Simplified installation scripts by moving shared distribution cleaning 
    code into the "cleandist.sh" script. Updated the "install.sh" script to 
    set the installation prefix to "/usr" on Debian systems. Updated the 
    Linux RPM spec file in order to clean the building directory after the 
    package creation.


2.30.4 - August 22, 2007

    Allow the argument of {}/1 calls to be a variable at compile time.

    Updated the Qu-Prolog config file to match and require version 8.1 and 
    added a "qplgt" integration script.

    Updated the XSB config file to match and require version 3.1 and to 
    take advantage of the compiler option optimize/1 when loading Logtalk 
    generated Prolog intermediate files.

    Added a new library object, "lgtunit", providing preliminary support for 
    writing and running unit tests. Added a new example, "testing", defining 
    sample unit tests.

    Added a new multi-threading example, "threads/tak", implementing the 
    Takeuchi function (recursive arithmetic).

    Updated the "threads/philosophers" example to use notifications instead 
    of a dynamic predicate for representing chopstick availability. Added an 
    alternative implementation using a parametric object. Improved example 
    documentation.

    Updated the "benchmarks" example to allow comparisons between calls to 
    imported category predicates and calls to local object predicates.

    Updated Emacs support in order to fix problems with the syntax-coloring 
    of some Logtalk built-in predicates and applied a patch contributed by 
    Nicolas Pelletier to workaround a compatibility problem with XEmacs.

    Updated jEdit support in order to fix a problem with the syntax-coloring 
    of the :/1 control construct.


2.30.3 - July 9, 2007

    Updated the multi-threading built-in predicate threaded/1 to support 
    both conjunctions of goals (akin to and-parallelism) and disjunctions 
    of goals (akin to or-parallelism) as an argument.

    Removed the experimental threaded_race/1 multi-threading built-in 
    predicate (its or-parallelism functionality is subsumed by the updated 
    threaded/1 predicate).

    Corrected a bug in the implementation of the multi-threading built-in 
    predicate threaded_exit/1 when there are more than one thread running 
    the same non-deterministic goal (the fix ensures that all alternative 
    solutions per threaded_exit/1 call come from the same computing thread). 
    Thanks to Paul Crocker for the suggested bug fix solution.

    Updated the sample queries in the "threads/buffer"/SCRIPT.txt" file to 
    match the updated entities in the example.

    Updated the "threads/functions" example to use the new version of the 
    threaded/1 multi-threading built-in predicate.


2.30.2 - June 24, 2007

    Updated the Logtalk compiler to throw a compilation error when duplicated 
    or conflicting predicate scope directives are found.

    Updated the Logtalk compiler to correct a cosmetic glitch when reporting 
    compilation errors.

    Updated the Logtalk compiler to check for mismatches between the argument 
    of this/1 calls and the parametric object identifier.

    Corrected a bug in the implementation of the multi-threading built-in 
    predicate threaded_ignore/1.

    Revamped the "threads/buffer" example to support setting the buffer 
    maximum number of items.

    Added a new DCG example, "dcgs/morse.lgt", for parsing messages in Morse 
    code.

    Extended the "parametric" example to illustrate a solution for dealing 
    with inheritance when defining "setter" predicates/methods that return 
    updated object identifiers.


2.30.1 - June 12, 2007

    Added a new, experimental control construct, :/1, for calling imported 
    category predicates without using message sending mechanisms.

    Added preliminary support for static binding when calling imported 
    category using the new :/1 control construct for categories compiled 
    and loaded using the compiler option "reload(skip)".

    Added a new control construct, <</2, which allows proving a goal within 
    the context of a specified object. Useful for debugging and for writing 
    object unit tests.

    Improved multi-threading support in order to make the built-in predicate 
    threaded_exit/1 generate an exception instead of blocking indefinitely 
    waiting for a reply from a non-existing thread.

    Updated the Logtalk compiler to generate an error when compiling from a 
    source file new definitions for built-in entities.

    Updated the Logtalk compiler to generate simpler clauses for the book-
    keeping table of local predicate definitions for parametric entities.

    Updated the config files for ECLiPSe, Ciao Prolog, SICStus Prolog, 
    SWI-Prolog, and YAP to use the renamed hook predicates introduced in 
    Logtalk 2.30.0 for parsing Prolog proprietary directives.

    Updated the "benchmarks" example to compare the performance of calls to 
    imported category predicates when using a message to "self" and a direct 
    call.


2.30.0 - May 28, 2007

    Added preliminary support for static binding when sending messages to 
    objects compiled and loaded using the compiler option "reload(skip)".

    Allow non-instantiated arguments at compile time for the multi-threading 
    built-in predicate threaded/1.

    Simplified and optimized the implementation of Logtalk multi-threading 
    support. Use a single dispatcher thread for all objects instead of each 
    object running its own dispatcher in order to minimize the number of 
    created threads (which can be problematic on 32 bits systems). Updated 
    the built-in predicate threaded/1 to make it deterministic and opaque to 
    cuts (similar to once/1).

    Updated the Logtalk built-in database methods to always interpret rules 
    whose body is the control construct true/0 as facts. Corrected a bug when 
    compiling dynamic predicates that would prevent using of the clause/2 
    built-in database method. Corrected a bug when using the Logtalk built-in 
    database method clause/2 with entities compiled in debug mode. Improved 
    predicate lookup caching when asserting and retracting dynamic facts.

    Improved detection and reporting of entity existence errors.

    Added a quit option, "q", to the Logtalk built-in debugger. Modified 
    the debugger behavior to automatically switch to trace mode when a spy 
    point is found.

    Added two new compiler options, "xmldir" and "tmpdir", allowing per 
    project definition of directories for storing XML documenting files 
    and for storing intermediate compilation files (e.g. Prolog files).
    Removed the config file predicate '$lgt_alt_directory'/2.
    Older config files are incompatible with this new Logtalk version.

    Added a shortcut to the Logtalk built-in predicate logtalk_load/1, {}/1,
    to all config files (defined there in order to be easy to comment it out 
    in case of conflict with some Prolog native feature or lack of compliance
    with the ISO Prolog standard regarding the definition of the {}/1 syntax.

    Allow the compiler flag "misspelt" to be set to "error".

    Updated the Logtalk compiler to not try to clean-up the dynamic predicates
    of redefined entities when reloading source files. Most Prolog compilers 
    already behave as expected when reloading the intermediate Prolog files 
    generated by the Logtalk compiler. For those Prolog compilers that do not 
    replace old definitions for dynamic predicates with the new ones, it is 
    not possible for Logtalk to implement a workaround that would work 
    correctly in all cases. Consult the "configs/NOTES.txt" file for more 
    information.

    Corrected a bug that prevents abolishing a dynamic entity loaded from a 
    source file. Thanks to Victor Noel for the bug report.

    Renamed the '$lgt_copy_pl_directive'/1 and '$lgt_rewrite_pl_directive'/2 
    config files predicates to '$lgt_rewrite_and_copy_pl_directive'/2 and 
    '$lgt_rewrite_and_recompile_pl_directive'/2. 

    Updated the config file for B-Prolog to match (and require) the new 7.0 
    version; updated and simplified the corresponding integration scripts.

    Updated the XSB POSIX integration script to automatically detect if we 
    are running the XSB stable version of the XSB CVS version.

    Added basic support for tabling to the config files of B-Prolog, XSB, 
    and YAP. Added a simple example of using tabling directives within 
    objects.

    Updated the SWI-Prolog and YAP config files to automatically detect if 
    the Prolog systems have been compiled with multi-threading support and 
    to set the Logtalk compiler flag "threads" accordingly.

    Corrected a bug when running Logtalk with SWI-Prolog that prevented the 
    use of alternative compilation directories (i.e. turning on the "altdirs" 
    compiler flag). Corrected a bug when running Logtalk with SWI-Prolog that 
    can prevent make/0 from recompiling and reloading modified Logtalk source 
    files. Updated the SWI-Prolog integration script, "swilgt.sh", to more 
    reliably detect the compiler executable name.

    Added a "configs/swi_set_logtalk_context.pl" file defining a useful but 
    fragile hack implementing a set_logtalk_context/1 built-in predicate for 
    switching the Logtalk top-level execution context to objects other than 
    the default pseudo-object "user" (you may use it as a debugging tool).

    Updated the CxProlog config file to use the new built-in predicates in 
    version 0.95. Added a shell script, "cxlgt.sh", for easy integration of 
    Logtalk with CxProlog on POSIX systems (with the help of Artur Miguel 
    Dias, CxProlog author).

    Updated the Ciao, K-Prolog, and ECLiPSe config files to set the default 
    value for the compiler flag "underscore_vars" to "dont_care" in order to 
    avoid spurious warnings with some of the provided examples.

    Added a config file and integration scripts for the current XSB CVS 
    version (3.0.1+), which supports some features needed by Logtalk not 
    present in the current stable version (namely, expansion of environment 
    variables).

    Added predicates depth/2 and variant/2 to the library object "term".

    Much improved "benchmarks" example, updated to allow running tests in 
    three different scenarios: event support on, event support off, and 
    using static binding. Moreover, metacalls are no longer used to run 
    the benchmark goals, resulting in more meaningful and accurate results.

    Removed all the "make_*lgt.*" and "makeall_lgt.*" shell scripts, replaced 
    by pre-made integration scripts that can be found on the new "integration"
    directory. Removed the "lgt_install.js" script. Renamed the POSIX install 
    and uninstall scripts to, respectively, "install.sh" and "uninstall.sh".
    Updated the integration, uninstall, and user-setup POSIX shell scripts 
    to use "$prefix/share/logtalk" as the default installation directory to 
    better comply with the Filesystem Hierarchy Standard 2.3 for UNIX-like 
    operating systems.

    Updated the integration scripts to automatically call the "cplgtdirs" 
    script when the Logtalk user directory cannot be located.

    Updated the integration, documentation, uninstall, and user-setup POSIX 
    shell scripts to try to locate the Logtalk installation directory and the 
    Logtalk user directory when the environment variables LOGTALKHOME and 
    LOGTALKUSER are not set.

    Updated the "install.sh" POSIX shell script to better clean and sanitize 
    the file permissions on the installation directory.

    Updated the "build_release.sh" POSIX shell script to also build a Debian 
    binary installer package (experimental).

    The Windows GUI installer no longer spans command-line shells running 
    JScript scripts to build the Prolog integration shortcuts. This hopefully 
    solves issues with security software silently blocking and breaking the 
    Logtalk installation.

    Added basic syntax coloring support for the GNU Nano 2.x text editor.


2.29.5 - March 28, 2007

    Added a new built-in predicate, threaded/1, for proving each goal in 
    a conjunction in its own thread, simplifying common multi-threading 
    tasks that previously required sequences of calls to the built-in 
    predicates threaded_call/1 and threaded_exit/1.

    Simplified and optimized the implementation of Logtalk multi-threading 
    support.

    Simplified implementation of the database built-in methods. Simplified 
    caching of dynamic predicate lookups. Improved performance of the 
    built-in methods retract/1 and retractall/1.

    Simplified the code generated when compiling entities in debugging mode.

    Corrected a bug in the built-in debugger when processing actions at a 
    port that implies reading a port action again (e.g. print exception term,
    print debugging status, and help options). Allow the debugger command 
    "skip" to work as the command "creep" in ports other than "call" and 
    "redo". Added a new debugger command, "ignore". Suspend debugging when 
    using the "break" debugger command.

    Generate a compilation error instead of just printing a warning when 
    compiling calls to the multi-threading built-in predicates within an 
    object with no threaded/0 directive present.

    Corrected a bug when compiling entities containing synchronization 
    directives on single-threaded Prolog configurations.

    Improving reporting of working directory when loading or compiling source 
    files by expanding any environment variables occurring in the path.

    Added a new compiler option, "reload", for defining the Logtalk behavior 
    when reloading source files. Valid values are "always" (default value; 
    defined in the config files) and "skip".

    Updated the programming examples to use the new "reload" compiler option 
    when loading library entities. Simplified loading of example source files 
    (by updating the utility loader files to automatically load all required 
    library files).

    Updated GNU Prolog config file to take advantage of some built-in list 
    predicates (requires version 1.2.14 or later); changed the compiler flag 
    "underscore_vars" value to "dont_care" to avoid spurious warnings with 
    some examples.

    Added a config file for B-Prolog 7.0b1.

    Updated the POSIX integration shell scripts to pass along any command 
    line options to the corresponding Prolog compiler and to prevent some 
    problems with paths containing spaces.

    Much improved syntax coloring and code completion support for the jEdit 
    text editor.

    Updated the "threads/primes" example to use the new "threaded/1" built-in 
    predicate. Updated the "threads/birthdays" example to better illustrate 
    the use of the built-in multi-threading predicates. Added a new 
    multi-threading example, "msort", implementing single-threaded and 
    multi-threaded versions of the merge sort algorithm.

    Expanded the "operators" example to illustrate a simple solution for 
    making operators local to source files (but global to all entities 
    defined within the source files).


2.29.4 - February 19, 2007

    Added a new library category, "listing", defining listing/0 and 
    listing/1 methods for helping in debugging tasks.

    Added two new experimental multi-threading predicates, threaded_wait/1 
    and threaded_notify/1, which allows suspension of a thread's goal until  
    a notification is received. Added two new examples, "threads/buffer" and 
    "threads/blackboard", illustrating the use of these predicates.

    Simplified and changed implementation of the threaded built-in 
    predicates in order to ensure that the threaded/0 directive is only 
    required on objects calling these predicates.

    Only print a warning for a missing threaded/0 directive for objects.

    Corrected a ordering bug on the entity initialization goal that 
    prevented using an object initialization goal that make use of 
    the object thread. 

    Corrected a bug when asserting rules into an object's database that 
    resulted in only the first asserted rule being visible when calling 
    the predicate through message sending. Thanks to Parker Jones for 
    the bug report.

    Corrected a bug when compiling dynamic entities (defined in source 
    files using the dynamic/0 directive) where declared predicates would 
    be wrongly compiled as static instead of dynamic.

    Updated the "make_xsblgt.sh" integration script again to fix an 
    additional problem resulting from the lack of support in XSB for 
    using environment variables in file paths.

    Added minimal support for using Exuberant Ctags with Logtalk.

    Added auto indent support to the jEdit text editor.

    Added support for listing public predicates in the "Functions" window 
    of the SuperEdi text editor.

    Converted TextMate code snippets from the old Property List format 
    to XML in order to provide compatibility with the "e" Windows text
    editor.

    New example: 99 bottles of beer on the wall! Sing along!


2.29.3 - January 15, 2007

    Corrected a bug in the Logtalk compiler optimizer code which was 
    discarding some declaration and definition catchall clauses needed 
    by the Logtalk built-in database methods when there is no initial 
    declaration and definition for the referenced dynamic predicates.
    Thanks to Parker Jones for the bug report.

    Corrected a bug in the compilation of empty, standalone protocols 
    and categories.

    Updated the "make_xsblgt.sh" integration script to workaround 
    the lack of support in XSB for using environment variables in 
    the argument of the reconsult/1 predicate.

    Corrected a bug in the "potions.lgt" example puzzle that prevented 
    its solution of being found.


2.29.2 - January 10, 2007

    Silently compile synchronized predicates as normal predicates on 
    single-threaded Prolog compilers.

    When using the threaded_race/1 predicate, competing threads are 
    now created detached.

    Corrected a bug that resulted in a loading error when reloading 
    source files defining threaded objects.

    Corrected a bug in the implementation of the built-in predicate 
    threaded_peek/1 that prevented alternative solutions from being 
    retrieved using the built-in predicate threaded_exit/1. Removed 
    the built-in predicate threaded_discard/1.

    The library object "random" is now a synchronized object. Updated 
    the "philosophers" multi-threading example accordingly.

    Dropped loading of broken "cleanup" library from the YAP config file 
    (the call_cleanup/2 predicate, required for Logtalk multi-threading, 
    is now available as a built-in predicate in the YAP CVS version).


2.29.1 - December 28, 2006

    Added a Logtalk version of John Fletcher's Prolog XML parser (see the 
    folder "contributions/xml_parser").

    Added shell scripts for helping building the distribution files of a 
    new Logtalk release. Updated the MacOS X installer package to set 
    default values for the Logtalk environment variables. Corrected a bug 
    in the "logtalk.spec" file where the default value for the LOGTALKUSER 
    environment variable only worked for the user doing the RPM installation.

    Corrected a bug in the reporting of the line number where a compilation 
    error (or warning) occurred. Extended support for reporting warning and 
    error line numbers to Quintus Prolog, Ciao Prolog, Qu-Prolog, and 
    ECLiPSe.

    Corrected a bug when using partial lists with the predicates nth0/3-4 
    and nth1/3-4 provided by the "list" library object.

    Improved "philosophers" multi-threading programming example.


2.29.0 - December 18, 2006

    Added a new built-in, empty object named "logtalk", which can play the 
    role of both a class and a prototype. It may be used to define class 
    hierarchies without forcing the use of metaclasses or reflective 
    designs.

    Added a built-in protocol named "monitoring" with declarations for 
    the before/3 and after/3 public event handler predicates. Updated 
    the Logtalk compiler to print a warning when defining an event handler 
    with no reference to the "monitoring" protocol.

    The default value of the compiler flag events/1 is now off. As most 
    applications do not use events, this setting ensures the best possible 
    message processing performance for those applications.

    Removed the experimental threaded_call/2 and threaded_exit/2 thread 
    predicates, replaced by new threaded_once/1, threaded_ignore/1, 
    threaded_race/1, threaded_peek/1, and threaded_discard/1 predicates.
    Renamed predicate directive atomic/1 to synchronized/1. Added new 
    entity directive synchronized/0. Added support for new "synchronized" 
    and "threaded" entity properties.

    Corrected a bug when using threaded calls as initialization goals 
    within threaded objects.

    Corrected an elusive bug in the Logtalk compiler where a source file 
    may not be properly closed when it contains a syntax error (thanks 
    to Robert Shiplett for the bug report).

    Corrected a bug in the implementation of the built-in methods retract/1 
    and retractall/1 that could result in unexpected exceptions. Updated 
    the built-in method assertz/1 to always use the lookup cache.

    Corrected a bug in the compilation of empty classes that are not 
    instances of a metaclass.

    Corrected a bug in the built-in method predicate_property/2 where some 
    predicate properties may not be returned when enumerating properties 
    using backtracking.

    Modified the SWI-Prolog config file and integration scripts to set 
    the flag "iso" to "true". Corrected an elusive bug in the definition 
    of predicate '$lgt_directory_exists'/1 that resulted in "library not 
    found" errors when loading Logtalk source files from within the 
    SWI-Prolog initialization file (thanks to Robert Shiplett for the bug 
    report).

    Updated the K-Prolog config file to workaround a problem when using 
    library notation due to failure to check directory existence with the 
    provided "libpaths.pl" file.

    Added a RELAX NG file describing the structure of the XML documenting 
    files generated by Logtalk.

    Corrected a bug in the Logtalk DTD file (missing "copyright" tag 
    declaration).

    Corrected a bug in the lgt2*.js scripts where the "custom.ent" file 
    was not being copied when generating (X)HTML and PDF files.

    Added a new multi-threading example, "philosophers", illustrating a 
    possible implementation of the "dining philosophers" problem.

    Improved the "metapredicates" example in order to illustrate the use 
    of closures instead of goals as meta-arguments.

    Added a reference to the "e" Windows text editor, which supports 
    the MacOS X TextMate 1.x text editor syntax configuration files.
    
    Updated the manuals index pages in order to workaround browsers bugs 
    with parsing of empty "span" tags (e.g. Internet Explorer and Opera).


2.28.2 - November 6, 2006

    Corrected a compiler bug where unknown entities will not be report when 
    compiling a source file whenever an entity with the same name but of a
    different type is already known.

    Added a XPCE hook file ("configs/xpcehook.pl") supporting Logtalk message 
    sending goals as XPCE call-back goals. The XPCE library is now loaded by 
    default by the SWI-Prolog integration scripts.

    Added support for generating single PDF files of the User and Reference 
    Manuals. Removed the PDF versions of the individual manual XHTML pages.

    The ECLiPSe config files now require release 5.10#26 or a later version.

    Added support for listing Logtalk entity names (objects, categories, and 
    protocols) in the SubEthaEdit symbols menu.

    Added a Vim dictionary file for Logtalk keyword completion and support 
    for automatic indentation.

    Added basic support for the MacOS X Smultron text editor. Added basic 
    support for the Notepad++, SuperEdi, and ConTEXT Windows text editors.


2.28.1 - October 10, 2006

    Added support for using XML entities using the notation "{entity name}" 
    in info/1 documenting directives for the "author", "copyright", and 
    "license" keywords. The XML entities are defined on a "custom.ent" file.

    Updated Logtalk bibliographic references (in file "BIBLIOGRAPHY.bib").

    Added a "lgt_uninstall.sh" shell script for uninstalling Logtalk on POSIX 
    operating systems.

    Improved RPM install-time messages on the defined Logtalk environment 
    variables.

    Updated the ECLiPSe integration scripts and config files to work with 
    and require version 5.10 (the first open source version of ECLiPSe).

    Corrected a typo on the "logtalk.dtd" file that prevents validation of 
    XML documenting files that use a local reference to the DTD.


2.28.0 - September 28, 2006

    Updated the Logtalk license to the final version of the "The Artistic 
    License 2.0" (see http://www.perlfoundation.org/legal/ for details).

    Added experimental support for multi-threading programming on selected 
    Prolog compilers. Added a new object directive, threaded/0, a new 
    predicate directive, atomic/1, and four new built-in predicates, 
    threaded_call/1-2 and threaded_exit/1-2. Added a new set of examples, 
    "threads". Thanks to Paulo Nunes for helping developing and testing 
    these new features.

    Expanded support for meta-predicates by allowing the declaration of meta-
    arguments as closures instead of goals.

    Added the generalized call/N predicate as a built-in method. This built-in 
    method must be used in the implementation of meta-predicates which work 
    with closures instead of goals.

    The metapredicate/1 directive should be considered deprecated. Use the 
    meta_predicate/1 directive instead.

    Updated the Logtalk compiler to generate an error whenever a non-variable 
    meta-argument is found in a clause head of a user-defined meta-predicate.

    Improved compilation of meta-predicate meta-arguments. Corrected a bug 
    in the compilation of user meta-predicates that allowed illegal calls 
    to non-public predicates on the caller object to be made from the object 
    defining the meta-predicates. Thanks to Rémy Haemmerlé and François 
    Fages for reporting the problem.

    Improved performance for non-cached messages, notably when running with 
    YAP, GNU Prolog, and SWI-Prolog on all operating systems and with SICStus 
    Prolog 4.0 on POSIX operating systems.

    Updated the Logtalk compiler to generate an error whenever a predicate 
    directive appears in a source file after predicate clauses that call the 
    predicate specified in the directive.

    Added support for "copyright" and "license" keys to the info/1 entity 
    documenting directive.

    Improved compiler error messages to also report source file line number 
    for selected Prolog compilers.

    Added PDF versions of all the manual XHTML pages. Added links to all the 
    manual XHTML pages to the corresponding PDF versions.

    Corrected a bug (introduced in version 2.27.0) in the built-in predicates 
    abolish_object/1, abolish_protocol/1, and abolish_category/1 that resulted
    in some clauses not being retracted when an object is abolished (thanks to 
    Neng-Fa Zhou for the bug report).

    Corrected a bug (introduced in version 2.27.1) in the processing of the 
    term_expansion/2 predicate.

    Corrected a bug in the compilation of redefined built-in predicates with 
    no clauses.

    Added an experimental config file for CxProlog 0.93.1.

    Updated the SWI-Prolog config and hook files in order to support the 
    edit/1 and make/0 development predicates.

    Changed the Logtalk - SWI-Prolog integration scripts to load the hook 
    file "swihook.pl" after the other files in order to avoid some possible 
    errors at startup.

    Updated the config file for the forthcoming SICStus Prolog 4.0 version 
    to work in the current beta version. Modified the "make_sicstuslgt.*" 
    shell scripts to work with both SICStus Prolog 3.12 and 4.0 versions.

    Updated the config file for YAP to workaround a problem on the Windows 
    version where testing for directory existence fails if the path ends with 
    a slash (or a double backslash); this problem prevents the use of library 
    notation to load source files (problem already fixed in the current YAP 
    CVS version).

    Updated the config file for B-Prolog to match (and require) the new 6.9 
    version; added integration shell scripts (for both Windows and POSIX 
    systems).

    Updated the config files and the integration scripts for ECLiPSe in order 
    to workaround bugs on the predicates abolish/1 and canonical_path_name/2.
    Modified the "make_eclipselgt.js" script to work with both ECLiPSe 5.8 
    and 5.9 versions.

    Dropped support for versions of XSB older than 3.0. Added support for 
    smart compilation of source files to the XSB config file.

    Updated the config file for IF/Prolog 5.1 by adding a missing definition 
    for predicate retractall/1 and avoiding some harmless singleton warnings.

    Add a ".txt" extension to all "NOTES" and "SCRIPT" files.

    Extended "dcgs", "parametric", and "metainterpreters" examples.

    Added Inno Setup GUI Windows installer script.

    Update all the JScript scripts to check if a compatible version of WSH 
    is installed and to workaround some problems with spaces in file paths.

    Updated the "lgt_install.js" JScript script to copy the scripts/*.bat and 
    the xml/*.bat batch scripts to the system's Windows directory instead of 
    modifying the PATH environment variable.

    Updated the "cplgtdirs.*" shell scripts to make a backup copy of any 
    previous LOGTALKUSER directory.

    Added post-install scripts to the LINUX RPM "logtalk.spec" file for 
    setting the environment variable LOGTALKHOME for all users, defining 
    a default value for the environment variable LOGTALKUSER, and running 
    the Prolog integration scripts.

    Split the installation and customization instructions in two files, 
    "INSTALL.txt" and "CUSTOMIZE.txt".

    Added shell scripts for converting the manual XHTML pages into PDF files 
    using CSSToXSLFO.


2.27.1 - March 27, 2006

    Allow calls to the built-in method parameter/2 with the first argument 
    not instantiated at compile time. Detect and report as a compilation 
    error parameter/2 indexes that are out of range.

    Optimized generation of predicate definition and declaration linking 
    clauses, resulting in small lookup performance improvements and in space 
    savings for the Prolog code generated when compiling Logtalk entities.

    Many minor code and documentation improvements to the Logtalk compiler.

    Added an object version of the tokenizer described in the Michael 
    Covington's paper "Tokenization using DCG Rules" to the "dcgs" example.

    Improved integration code for Qu-Prolog and Logtalk ("configs/qphook.ql").

    Improved library hierarchy methods that return lists of objects in order 
    to avoid duplicated elements (library objects "proto_hierarchy.lgt" and 
    "class_hierarchy.lgt"). Added new methods extension/1 and extensions/1 to 
    the library object "proto_hierarchy.lgt".

    Documented the concept of "parametric object proxy". Added a new example, 
    "proxies", illustrating the use of parametric object proxies.

    Added support for code completion and for listing entity names on the 
    symbol pop-up menu to the MacOS X TextMate text editor.

    Updated the "cplgtdirs.*" scripts to also create an alias/shortcut to the 
    "wenv" directory.

    Renamed the alternative compilation and documentation directory names on 
    all config files to be compatible across operating-systems. Removed unused
    predicate '$lgt_reverse'/2 from all config files.

    Updated HTML manuals "print.css" CSS file for compatibility with the 
    latest version of CSSToXSLFO.


2.27.0 - February 9, 2006

    Improved performance for local calls to the built-in methods phrase/2-3.
    Allow the built-in methods phrase/2-3 to accept both partial and proper 
    lists of terminals.

    Improved grammar rule translator. Report calls to undefined non-terminals 
    when translating grammar rules.

    Added support for declaring grammar rule non-terminal aliases using the 
    alias/3 directive.

    Added a new predicate property, non_terminal/1, for predicates resulting 
    from the compilation of grammar rule non-terminals.

    Improved support for the built-in method expand_term/2 in order to allow 
    bypassing of the default Logtalk grammar rule translator by defining 
    clauses for the term_expansion/2 predicate. Added a "term_expansionp" 
    protocol to the Logtalk library. Added a new example, "expansion", 
    illustrating the use of the term_expansion/2 predicate.

    Added a new compiler flag, hook/1, allowing the specification of a 
    compiler hook that is called for which term read from a source file.
    Added a simple example, "hooks", of using the Logtalk compiler hook 
    to expand author abbreviations in info/1 directives into full names 
    and email addresses.

    Added support for XSB 3.x to the runtime error handler. Updated the XSB 
    3.x config file with declarations for multi-threading meta-predicates.
    
    Removed a few choice-points when checking validity of entity directives.

    Added two new objects, list(Type) and set(Type), to the standard library 
    supporting the validation of lists and ordered sets whose elements are 
    restricted to a single type.

    Added a new DCG example for solving enigmas encoded using a cellphone 
    keypad.

    Added a missing library dependency to the "puzzles" example SCRIPT file.

    Removed the experimental "systemp.lgt" protocol from the list of files 
    loaded by the "library/all_loader.lgt" loader utility files to avoid 
    compilation errors on some Prolog systems.

    Corrected a bug that prevented dynamic creation of categories using the 
    built-in predicate create_category/4.

    Corrected a bug in the reporting of singleton variables, which failed to 
    write an accurate message for facts and grammar rules.

    Corrected a bug in passing the correct calling context ("this") when 
    processing meta-calls in objects.

    Corrected a bug in scope checking with local calls to reflection and 
    database methods.

    Corrected a bug in checking the validity of the arguments of the op/3 
    directive appearing inside entities.

    Added predicates for testing if a term is a partial list or a proper list 
    to all config files.

    Added a definition for missing open/4 ISO Prolog predicate to the config 
    file of Bin Prolog.

    Added a workaround for a B-Prolog bug to this compiler config file.


2.26.2 - December 20, 2005

    Improved error-checking for the Logtalk compiler and for the grammar rule 
    translator.

    Small performance improvements for message sending and for the built-in 
    database methods.

    Corrected a bug on the implementation of the built-in methods phrase/2-3 
    for negated grammar rule bodies (thanks to Mats Carlsson for pointing the 
    error).

    Removed the read-only compiler flag "iso_initialization_dir".

    Corrected a compilation bug on the "metapredicates" example source file.
    Corrected several bugs on the performance monitor of the "searching" 
    example.

    Switched off default generation of XML documenting files for the "symdiff" 
    example in order to avoid file names compatibility problems on Windows.

    Updated compatibility notes on B-Prolog 6.8 and Qu-Prolog 7.0. Added a 
    config file for the forthcoming SICStus Prolog 4.0 version (based only 
    on publicly available information). Updated the config file for Amzi! 
    Prolog to solve issues with predicate properties and to ensure that file 
    system utility predicates are loaded.

    Added a config file for the current XSB CVS version and the corresponding 
    integration shell scripts (for both Windows and POSIX systems). Modified 
    the "cplgtdirs.*" shell scripts in order to make either links or copies of
    the config files and the "libpaths.pl" file with the required ".P" file 
    name extension.

    Improved integration scripts documentation and help screens.

    Added a predicate for checking directory existence to the config files.


2.26.1 - November 28, 2005

    Added a CSS style-sheet to the Logtalk XHTML documentation that can be 
    used with CSSToXSLFO to generate nicely formatted PDF files suitable for 
    printing with running headers and page numbers.

    Updated the Logtalk XHTML documentation for compliance with the XHTML 1.1 
    standard.

    Updated the "lgtxhtml.xsl" XSLT file in order to generate XHTML 1.1 files.

    Added a new, generic "lgtpdf.xsl" XSLT file. Redefined the "lgtpdfa4.xsl" 
    and "lgtpdfus.xsl" files to import the "lgtpdf.xsl" file.

    Added support for the Lunasil XSL-FO processor to the "lgt2pdf.*" shell 
    scripts.

    Updated the "lgt2pdf.sh", "lgt2xml.sh", and "lgt2html.sh" shell scripts 
    in order to write a warning message when the current directory does not 
    contain any XML documenting file.

    Added a definition for missing open/4 ISO Prolog predicate to the config 
    files of Open Prolog, LPA Prolog compilers, and MasterProlog.


2.26.0 - November 7, 2005

    Added support for defining predicate aliases when using uses/2 directives
    (using the format Predicate::Alias).

    Added Prolog modules migration code allowing modules to be compiled as 
    objects and allowing messages to be sent to modules. Added a new "modules"
    example.

    Added a "Prolog Integration and Migration Guide" to the Logtalk 
    documentation.

    Added support for syntax coloring of common Prolog module directives to 
    the configuration files of the supported text editors.

    Added support for using library aliases on the second argument of the 
    logtalk_library_path/2 predicate (using the format alias(path)).

    Added support for ignoring, copying as-is, or rewriting proprietary Prolog
    directives. The action to be taken is defined on a per-directive basis on 
    the config files.

    Updated the config files of CIAO, ECLiPSe, SWI-Prolog, and YAP to define 
    actions for some proprietary directives in order to allow some or most of 
    the module libraries distributed with these compilers to be compiled as 
    objects.

    Renamed some XML documentation-related compiler flags to more meaningful 
    names: "xml" -> "xmldocs", "xsl" -> "xslfile", and "doctype" -> "xmlsref".
    No changes to the other flags or flag valid values.

    Updated documenting scripts to use system-wide resources from LOGTALKHOME
    and user-modifiable resources from LOGTALKUSER.

    Updated "cplgtdirs.*" shell scripts to create links to the documenting 
    scripts and to the DTD and XML Schema specifications instead of making 
    local copies. Updated the "cplgtdirs.js" Windows JScript script to create
    a link to the Logtalk manuals.

    Changed generation of predicate compiled functors to add an underscore 
    between the original predicate functor and arity (further minimizing the 
    chance of name conflicts).

    Improved compilation warning messages (separately handling plural and 
    singular forms).

    Improved documentation of Windows JScript installation and integration 
    scripts.

    Corrected a bug on the Logtalk built-in debugger on the processing of the
    abort option at a leashed port (option was ignored instead of aborting the
    debugging session).

    Added an option to choose between a "verbose" or "compact" listing of the 
    default compilation flags at Logtalk startup (defined on the config files).

    Improved CIAO integration scripts in order to suppress some (harmless) 
    warnings which are generated at first run.

    Updated SWI-Prolog hook file ("swihook.pl") in order to support Logtalk 
    library notation when loading Logtalk files using the SWI-Prolog consult/1 
    predicate.

    Corrected a bug on the implementation of the built-in method abolish/1 
    that prevented abolishing of dynamic predicates with arity zero.

    Corrected a bug on the "gplgt" shell script generated by the make_gplgt.sh
    shell script where the value of the LOGTALKHOME environment variable would
    not be retrieved at runtime.

    Removed config file for older versions of XSB (up to 2.6). Renamed the 
    config file for XSB 2.7.1 to simply "xsb.config".