root/tags/lgt2281/RELEASE_NOTES.txt

=================================================================
Logtalk - Object oriented extension to Prolog
Release 2.28.1

Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
=================================================================


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


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".

    Consolidated the source files of the "birds", "errors", "lpa", "lo", 
    "metainterpreters", "poem", "relations", "roots", and "symdiff" examples 
    into single source files. Updated the "searching" example to take advantage
    of the uses/2 directive.

    Removed outdated documenting shell scripts from the "xml" directory.

    Corrected a bug when compiling a source file where the generated Prolog 
    file might not be properly closed when a compilation error occurs.


2.25.3 - September 12, 2005

    Consolidated the source files of the examples "bricks", "dynpred", "mi", 
    "parametric", "points", "polygons", "reflection", "shapes", "sicstus", 
    and "viewpoints" into single source files.

    Improved documentation on most example source files. Improved "parametric"
    example by adding a new parametric objects and by illustrating alternative
    ways of accessing object parameters.

    Updated several config files with declarations for some more non-standard 
    Prolog meta-predicates.

    Corrected some omissions and typos on the B-Prolog - Logtalk integration 
    instructions.

    Small performance optimization for messages and super-calls with not yet
    cached method lookups.


2.25.2 - August 11, 2005

    Updated Logtalk installation and Prolog integration scripts in order to 
    detect a wrongly defined LOGTALKHOME environment variable.

    Corrected a bug on the lgt_install.sh and make*lgt.sh shell scripts where 
    the wrong variable was being referenced when testing the existence of the 
    installation directory prefix.

    Corrected a bug on the makeall_lgt.sh shell script that failed to properly
    detect unsuccessful completion of individual Prolog integration scripts. 


2.25.1 - August 8, 2005

    Added support for using the "source-highlight" package (version 2.0 or 
    later) by Lorenzo Bettini with Logtalk source files.

    Several optimizations to the syntax coloring configuration files of most 
    of the supported text editors. Added support for code folding to the Vim, 
    Kate, and TextMate text editors.

    Updated the SWI-Prolog shell integration script (make_swilgt.sh) to use 
    either "swipl" or "pl" as the name of the Prolog executable, depending 
    on the host operating system.

    Modified the way entity prefixes are generated for compiled code in order 
    to further minimize possible conflicts resulting from the same prefix being
    used for different entities (bug report and fix by Brian Hulley). Changes 
    to the prefix format are also reflected on the names of the automatically 
    generated XML documenting files.

    Updated the lgt2html.* and lgt2xml.* documenting scripts in order to index 
    parametric objects using the notation <entity>/<number of parameters>.

    Corrected a bug on the lgtxml.xsl XSLT file where links to related files 
    pointed to .html files instead of .xml files.

    Updated the lgt_install.sh and the make_*lgt.sh shell scripts to check and
    report invalid installation directory prefixes.

    Added a new state-space search problem, "salt3.lgt", contributed by Paula 
    Marisa Sampaio, to the "searching" example.


2.25.0 - May 23, 2005

    Logtalk compiler is now source file-based instead of entity-based. Thus, 
    a source file may now contain any number of entities, without the need of 
    using source metafiles. Therefore, this version drops support for source 
    metafiles and the .mlgt file name extension.

    The experimental encoding/1 directive, when used, must be the first term 
    on a source file.  Added an entry to the reference manual describing the 
    directive. Improved "encodings" example.

    Added a new method, debugging/1, to the "debugger" pseudo-object for 
    querying the system about entities compiled in debug mode.

    Improved source file and entity compilation and loading reporting. In 
    particular, when using library notation for source files, the Logtalk 
    compiler now prints the library path containing the source files being 
    compiled or loaded.

    Added new shell scripts, makeall_lgt.*, which run all the make_*lgt.* 
    shell scripts in sequence.

    Simplified compiler reporting of singleton variables in directives and 
    clauses.

    Added an adaption of the "timetables" LPA Prolog++ example.

    Updated B-Prolog config file for the new 6.7 #2 version. Dropped support 
    for older versions of B-Prolog.


2.24.0 - April 22, 2005

    Added experimental support for a encoding/1 directive for declaring the 
    text character encoding of a source file. This directive is fully based 
    on a directive with the same name and with similar semantics found on 
    recent development versions of SWI-Prolog. For now, this directive only 
    works with SWI-Prolog as most Prolog compilers lack support for dealing 
    with different text encodings. Added new flag "supports_encoding_dir". 
    Added a new example, "encodings", of using the new encoding/1 directive.

    When a source file contains an encoding/1 directive, the XML documenting 
    files will use the same encoding. When no encoding/1 directive is present,
    the XML documenting files will assume UTF-8 encoding.

    Added new info/1 documenting directive key, "parameters", allowing the 
    declaration of both parameter names and parameter descriptions. Added new 
    info/1 documenting directive key, "remarks", allowing general remarks 
    about an entity to be stated. Added new info/2 documenting directive key, 
    "arguments", allowing declaration of both predicate argument names and 
    predicate argument descriptions. Added new info/2 documenting directive
    key, "examples", allowing the representation of predicate call examples.

    Much improved and accurate reporting of non-portable predicate calls when 
    using the "portability" flag.

    Added a new directory to the Logtalk distribution, "contributions", which 
    will be used for user-contributed code. On this release, it contains an 
    implementation of the ISO 8601 standard by Daniel L. Dudley, providing a 
    library of useful date predicates.

    Added new lgt2xml.* shell scripts for generating (X)HTML indexes of XML 
    documenting files.

    Rewritten the lgtxhtml.xsl, lgthtml.xsl, lgtxml.xsl XSLT scripts in order 
    to make it easier to define alternative CSS files for the generated HTML 
    files. Rewritten the lgtpdfa4.xsl and lgtpdfus.xsl XSLT scripts in order 
    to improve appearance of the generated PDF files.

    Improved the documentation of the "benchmarks" example and added new 
    predicates for running batches of benchmark tests and for generating 
    lists of known size for the benchmark tests of static code.

    Corrected a bug in the lgt2html.*, lgt2pdf.*, and cplgtdirs.sh shell 
    scripts which resulted in failed transformations whenever the LOGTALKHOME 
    and LOGTALKUSER environment variables or the output directory contained 
    spaces or accented characters.

    Added workaround for Prolog compilers that define operators other than 
    ','/2 that cannot be redefined (such as new B-Prolog 6.7).

    Added a Logtalk "clip" file for the TextPad Windows text editor.

    Renamed directory "misc" to the more meaningful name "scripts".

    Corrected a bug in the implementation of the built-in database methods 
    asserta/1 and assertz/1 when asserting facts on objects compiled in debug 
    mode.

    Corrected a bug in the method leash/1 of the built-in pseudo-object 
    "debugger", which failed to accept an empty list as a valid argument.

    Corrected a bug in the header of the automatically generated XML 
    documenting files when using the XML Schema specification (logtalk.xsd), 
    which could prevented validation when the compiler flag "doctype" is set 
    to "web".

    Corrected a compilation bug where Prolog clauses written outside entities 
    on source metafiles would have their order reversed. Simplified splitting 
    of source metafiles.

    Corrected a compilation bug where Prolog clauses written before an entity 
    opening directive would not be copied to the generated Prolog file.

    Corrected a bug on the "roots" example in the object "class" which failed 
    to properly test the validity of new object identifiers.

    Corrected a bug in the syntax coloring file for the Vim text editor, which
    resulted in an error message when opening a Logtalk source file for the 
    first time.


2.23.1 - March 7, 2005

    Simplified message sending compilation, improving performance of both 
    entity compilation and runtime top-level message sending.

    Simplified implementation and improved performance of the built-in method 
    current_predicate/2.

    Updated the runtime error handler for top-level ::/2 calls to recognize 
    non-existing predicate exceptions thrown by XSB, SICStus Prolog, CIAO, 
    B-Prolog, and recent development versions of SWI-Prolog. Rewritten the 
    ::/2 predicate in order to minimize the overhead of the catch/3 calls 
    associated with the runtime error handler, thus improving performance.

    Expanded the benchmarks example to test performance of the built-in 
    database methods.

    Lookup caches are now cleaned before loading a redefined entity in order 
    to avoid potential problems with entity initialization goals containing 
    message sending calls (previous versions cleaned the caches only after 
    entity loading).

    When reloading an object, its tables of dynamic predicate declarations 
    and dynamic predicate definitions are now reseted.

    Corrected a compatibility problem with the "birds" example due to the use 
    of an operator not available in some Prolog compilers.


2.23.0 - February 21, 2005

    Optimized the code generated for local calls to the built-in predicates 
    asserta/1, assertz/1, retract/1, and retractall/1, when the argument is 
    a dynamic predicate declared by a scope directive in the object making 
    the calls.

    Added caching of predicate compiled forms for dynamic facts when used 
    with the database built-in methods clause/2, asserta/1, assertz/1, 
    retract/1, and retractall/1, resulting in a significant performance 
    improvement when using an object's dynamic database. Improved performance 
    of the database built-in methods abolish/1, asserta/1, assertz/1, clause/2, 
    retract/1, and retractall/1 when the cache is not used.

    Corrected a bug on the implementation of the built-in methods asserta/1 
    and assertz/1 that prevented asserting of rules.

    Corrected a bug on the implementation of built-in methods retractall/1, 
    retract/1, and clause/2 that allowed access to local dynamic predicates 
    from outside the container object.

    Added a runtime error handler for top-level ::/2 calls which tries to deal
    with exceptions thrown by calling non-existing predicates by translating 
    Logtalk generated internal predicate names to user names.

    Print the total number of warnings after a call to the Logtalk built-in 
    predicates logtalk_compile/1-2 and logtalk_load/1-2.


2.22.5 - February 9, 2005

    Added scripts for easy integration of Logtalk with K-Prolog. Updated the 
    K-Prolog config file, correcting a show-stopper bug and enabling support 
    for using the "library" notation for loading source files.

    Updated JIProlog config file in order to allow smart compilation of source
    files.

    Changed format of preprocessor and runtime dynamic predicates that deal 
    with predicate indicators for better performance.

    Simplified implementation of Logtalk built-in methods asserta/1 and 
    assertz/1.

    Corrected a performance bug with calls to built-in predicates from objects
    and categories.

    Corrected spurious backtracking occurring on some calls to the built-in 
    predicate define_events/5.

    Updated shell script "misc/cplgtdirs.sh" to prevent copy of Logtalk files 
    when the destination directory already exists (thus avoiding overriding 
    any user-modified files when upgrading Logtalk).

    Added syntax coloring for the predicate logtalk_library_path/2 to the 
    supported text editors. Updated the syntax coloring file for the TextMate 
    text editor, adding some missing ISO Prolog predicates.

    Improved printing of lists of unknown referenced entities, misspelt calls,
    and singleton variables when compiling source files. Simplified handling 
    of references to unknown entities.

    Added workaround for Prolog compilers with broken read_term/3 singletons/1
    option.

    Updated the Logtalk compiler/runtime and the documentation to always 
    use the expression "compiler flag" instead of "compiler option" for 
    consistency. Other minor documentation improvements.

    Corrected a bug with the abolishing of dynamic entities where the clauses 
    corresponding to the alias/3 directive are not being abolished.

    Added new predicates '$lgt_call'/9 and '$lgt_once'/9 to all config files.

    Simplified and improved performance of compilation of directives containing
    predicate indicators.


2.22.4 - January 12, 2005

    Simplified method lookup cache tables, resulting in a small message 
    sending performance speedup. Improved method lookup caching for 
    parametric objects. Added support for caching method lookups for 
    parametric objects whose parameters contain cyclic terms.

    Added a new category, "assignvars", to the Logtalk standard library, 
    containing an adaptation of the implementation of logical assignable 
    variables developed by Nobukuni Kino. Added a new example, "assignvars",
    illustrating some possible uses of assignable variables in the context 
    of parametric objects.

    Simplified compilation of op/3 directives: there is no longer need to 
    repeat the directives both before and inside an entity in order to make 
    the operators global and also use them in the compilation process.

    Simplified installation instructions.

    Corrected a compiler bug in the code that checks and prints a warning 
    when redefined parametric objects.

    Corrected a bug in the built-in predicate abolish_category/1, which 
    failed to delete import relation clauses between the category being 
    abolished and other categories.


2.22.3 - December 30, 2004

    Added a configuration file for XSB 2.7.

    Corrected a bug where the use of alternative compilation directories 
    would fail the first time the logtalk_compile/1-2 or logtalk_load/1-2 
    predicates are used for a given file or library.

    Corrected a bug in the built-in methods asserta/1 and assertz/1 when 
    asserting facts into an object being debugged, which resulted in wrong 
    execution context information being printed when tracing calls to 
    the asserted facts.

    Corrected a bug in the built-in methods asserta/1 and assertz/1 when 
    asserting rules into an object being debugged, which resulted in rule 
    bodies compiled with no information being printed for the rule head 
    when tracing calls to the asserted rules.

    Corrected a bug in the dynamic creation of objects, protocols, and 
    categories when the debug flag is on, which resulted in the table of 
    entities being debugged not being updated.

    Corrected a bug in the handling of exceptions thrown when using the 
    built-in debugger, which resulted in exceptions always being turned 
    into failures.


2.22.2 - December 24, 2004

    Improved performance of dynamic creation and compilation of objects, 
    protocols, and categories.

    Improved error-checking code of methods asserta/1 and assertz/1 to 
    prevent asserting of non-callable terms as facts.

    Improved error checking for documenting directives (info/1 and info/2).

    Improved the XSB integration script (make_xsblgt.sh) in order to use the 
    configuration file and the libpaths file available from the $LOGTALKUSER 
    directory.

    Improved installation instructions and installation scripts documentation.

    Added documentation to the user manual on describing predicate exceptions 
    using the info/2 directive.

    Corrected a bug in the predicate_property/2 built-in method when called 
    with the second argument instantiated to the alias/1 property.


2.22.1 - December 6, 2004

    Improved installation instructions. Updated the Windows installation 
    JScript script to add the Logtalk directories "misc" and "xml" to the 
    system PATH environment variable and to reuse the environment variable 
    LOGTALKUSER if already defined.

    Added helper batch scripts (misc/cplgtdirs.bat, xml/lgt2html.bat, and 
    xml/lgt2pdf.bat) for easily running the corresponding Windows JScript 
    scripts from the command-line (the two xml/lgt2*.bat scripts run the 
    corresponding *.js scripts stored in the %LOGTALKUSER%/xml directory 
    in order to support user customization).

    Updated the lgt2html.* and lgt2pdf.* shell scripts to use the environment 
    variable LOGTALKUSER instead of LOGTALKHOME for finding supporting files, 
    thus allowing for end-user customization of the scripts and their related 
    files.

    Added documentation on read-only compiler flags (which are defined in the 
    configuration files) to the User Manual.

    Updated the misc/lgt_install.js JScript installer script to workaround a 
    Windows Scripting Host bug which may result in broken shortcuts in the 
    created "Logtalk" program group.


2.22.0 - November 29, 2004

    Implemented a notion of library as simply a directory containing source 
    files. Added a new dynamic predicate, logtalk_library_path/2, for 
    specifying library paths. Added a sample file (libpaths/libpaths.pl) for 
    setting library paths for the Logtalk standard library and for all the 
    supplied examples.

    Added support for using the notation <library>(<entity>) with the built-in
    predicates logtalk_compile/1-2 and logtalk_load/1-2 for compiling and 
    loading source files contained on a library, without the need to first 
    change the current working directory.

    Changed the library and the examples loading instructions to use the new 
    notation <library>(<entity>).

    Improved installation instructions and installation scripts. Added a new 
    environment variable, LOGTALKUSER, for defining the location of the copies 
    of the user-modifiable Logtalk files in a multiple users setup environment.

    Added utility predicates to most configuration files for querying and 
    changing the current working directory (needed for the <library>(<entity>) 
    notation to work).

    Corrected a bug in the code that checks for file existence when compiling 
    or loading source files and source metafiles.


2.21.6 - November 15, 2004

    Added support for using alternative directories for storing the Prolog files 
    and the XML documenting files resulting from entity compilation. A new read-
    only flag, "altdirs", allows the support for alternative directories to be 
    turned on the configuration files of Prolog compilers providing the necessary 
    operating-system access predicates for implementing this feature.

    Improved installation instructions and reporting of default compilation flags 
    at startup.

    Added a sorely missing "Hello World!" example :-)


2.21.5 - November 2, 2004

    Added a new optimization compiler flag, "events", which can be used to switch 
    off event-driven programming support when not needed, on a per-object basis, 
    resulting in improved message sending performance.

    Small performance optimization to the runtime creation of dynamic objects, 
    protocols, and categories.

    Updated the error handling code of the built-in predicates create_object/4, 
    create_protocol/3, and create_category/4 in order to throw an instantiation 
    error when called with a non-instantiated argument.

    Updated the benchmarks example to calculate and subtract the benchmark loop 
    time in order to print absolute timings for the benchmarked goals.

    Updated the Qu-Prolog patching instructions to also convert Logtalk source 
    metafiles.

    Fixed a typo on the XSB compatibility notes in the configs/NOTES file.


2.21.4 - October 26, 2004

    Corrected a silly bug in the definition of the predicate repeat/1 on the 
    new "benchmarks" example.


2.21.3 - October 25, 2004

    Corrected a silly bug in message translation which resulted in a small 
    performance loss. Simplified implementation of message sending predicate 
    ::/2, resulting in a small performance improvement.

    Added a new section on message sending performance to the user manual.

    Added a new example, "benchmarks", for helping measuring performance of 
    Logtalk message sending between Prolog compilers and for comparing message 
    sending with predicate calls in plain Prolog and with calls to modules 
    predicates.

    Updated the YAP configuration file to hide some of the book-keeping tables 
    of the Logtalk runtime engine and to use statistics/2 instead of cputime/0 
    for more accurate timings.

    Updated the Logtalk shell installation script to create the $prefix/bin 
    directory if it does not exist.

    The lgt2pdf.sh and lgt2html.sh shell scripts now use "rm -f" when removing 
    the DTD and XSD files in order to avoid prompting the the user about the file 
    permissions.

    Updated the cplgtdirs.sh shell script to make all copied files user writable.


2.21.2 - October 18, 2004

    Added support for declaring grammar rule non-terminals as public, protected, 
    private, dynamic, or discontiguous using the notation Functor//Arity. Added 
    support for documenting non-terminals using the info/2 and mode/2 directives.

    Added support for a new alias/1 predicate property.

    New experimental config file for JIProlog 3.0 (see the configs/NOTES file 
    for details).

    Added a mode bundle for the TextMode 1.0.x (MacOS X) text editor providing 
    syntax highlighting, folding, and code snippets for editing Logtalk source 
    files. Corrected a bug in the syntax coloring of the :-/1-2 operator on the 
    SubEthaEdit 2.x text editor.


2.21.1 - September 27, 2004

    Added experimental support for a new built-in method, expand_term/2, which 
    allows access to the Logtalk grammar rule translator. Corrected bug in the 
    expansion of \+/1 in grammar rule bodies. Optimized code generated for 
    message sending calls in the body of grammar rules. Improved error handling 
    of the built-in methods phrase/2 and phrase/3. Added new section on definite 
    clause grammars to the user manual. Added two new objects to the "dcgs" 
    example, dcgtest and bypass, containing test cases for the Logtalk DCG 
    translator and illustrating some programming techniques with grammar rules.

    Corrected a bug in the implementation of the built-in method clause/2 which 
    prevented access to clauses of local dynamic predicates.

    Corrected some dead links on the XHTML manuals.

    Corrected a bug in the syntax coloring of numbers on the SubEthaEdit 2.x 
    text editor.


2.21.0 - September 14, 2004

    Added a new predicate directive, alias/3, which allows the definition of 
    alternative predicate names in order to improve readability of inherited 
    features and to solve conflicts between implemented, imported, or inherited 
    predicates.

    Added new example, "aliases", illustrating the use of the new alias/3 
    predicate directive for improving readability of inherited features.

    Added new example, "diamonds", illustrating problems and solutions for the 
    "diamond problem" (multi-inheritance conflicts and ambiguities) using the 
    new alias/3 predicate directive.

    Allow categories to import other categories, i.e. allow categories to be 
    defined as a composition of other categories. This feature should only be 
    used when extending a category without breaking its functional cohesion 
    (for example, when a modified version of a category is needed for importing 
    into several unrelated objects). 

    Added new example, "engines", illustrating importing a category from another 
    category.

    Updated the syntax coloring configuration files for the supported text 
    editors for the new alias/3 predicate directive.

    Added auto-complete strings for Logtalk methods and for Logtalk and Prolog 
    built-in predicates and directives to the SubEthaEdit 2.x text editor.

    Corrected a bug which prevented compilation of metafiles containing 
    parametric entities.


2.20.2 - August 31, 2004

    Added a Windows JScript script for installing Logtalk. Improved the Windows 
    JScript scripts used for easy integration of Logtalk with selected Prolog 
    compilers.

    Improved user manual section on defining object and category metapredicates 
    and on calling non-standard Prolog built-in metapredicates. Improved the 
    description of some compiler options.

    Added some files missing from the "errors" example (which should have been 
    included in the previous release).

    Added basic syntax coloring support for the BBEdit 8.x text editor.


2.20.1 - August 19, 2004

    Added Windows JScript scripts for easy integration of Logtalk with CIAO and 
    GNU Prolog.

    Added encoding attribute (set to UTF-8) to the xsl:output tag in the 
    lgtxml.xsl, lgthtml.xsl, and lgtxhtml.xsl files.

    Replaced the Windows JScript scripts lgt2pdf.js and lgt2html.js by their 
    final versions (the wrong ones shipped with Logtalk version 2.20.0).

    Updated the "errors" example to illustrate possible conflict errors when 
    using the uses/2 directive.

    Updated the RPM logtalk.spec file to use the .tgz archive extension.


2.20.0 - August 16, 2004

    Added support for the uses/2 predicate directive (whose semantics is similar 
    to C++ using-declarations). Updated the uses/1 entity directive to accept as 
    argument a single object identifier.

    Improved installation instructions for Windows users.

    Added four new sample bash shell scripts and Windows JScript scripts for 
    converting XML documenting files to PDF, HTML, and XHTML using several XSL 
    processors.

    Added missing namespace to XSL files in order to generated valid (X)HTML 
    files with recent versions of XSLT processors.

    Updated the User Manual documentation on converting XML documenting files 
    to other formats.

    Removed the texml.xsl XSLT file as the TeXMLatte application it depends on 
    is no longer available.

    Added Windows JScript script for copying the Logtalk examples, library, and 
    xml directories to the user directory.

    Added Windows JScript scripts for easy integration of Logtalk with ECLiPSe, 
    SWI-Prolog, SICStus Prolog, and YAP.

    Added missing extension for source metafiles to the SWI-Prolog hook file.
    
    Corrected a bug in the lgtxhtml.xsl XSLT file where a wrong reference to 
    the Logtalk CSS file is being used in the xml-stylesheet tag.

    The iso_initialization_dir/1 compiler option is now a read only flag, 
    defined in the configuration files.


2.19.1 - August 2, 2004

    Corrected a bug where entities could not be reloaded if they depend on 
    other, not yet loaded entities.

    Corrected a bug where compiler options would not be used when compiling 
    source metafiles.

    Corrected several typos on the Logtalk manuals.


2.19.0 - July 26, 2004

    Added support for defining more than one entity per file using Logtalk 
    source metafiles (*.mlgt), which the runtime engine automatically splits 
    on single entity source files plus loading and compiling helper files.

    Updated the URL used on the automatically generated XML documenting files 
    when compiling entities with the option doctype(web).

    Improved error checking when compiling calls to the {}/1 control construct.

    Corrected several typos and some outdated links on the Logtalk manuals.


2.18.0 - July 9, 2004

    Added caching of method lookups in order to improve message processing 
    performance (including messages to self and super calls). Applied several 
    optimizations to runtime translation of messages in order to further 
    improve performance.

    Improved error checking while parsing and compiling messages to self.

    Update ECLiPSe config files to compile the Prolog files generated by Logtalk 
    (when compiling source files) in optimized mode instead of traceable mode.

    Updated description of patches needed for running Logtalk with XSB, added 
    a shell script for easy integration of Logtalk with this Prolog compiler, 
    and corrected a problem with its corresponding config file.

    Added multifile/1 directive to the syntax coloring configuration files of the 
    supported text editors.


2.17.2 - June 14, 2004

    Updated the Logtalk compiler to allow compilation of source files which 
    contain only directives and no entity definition.

    Simplified loading of library and example entities by using Logtalk source 
    files as loader files.

    Some improvements to the documentation, including the QUICK_START file and 
    the User Manual for first-time users, and to the example descriptions.

    Corrected a bug in handling of local object operators that are also global 
    operators.

    Corrected a bug where dynamic directives are not being generated for dynamic 
    predicates that lack a scope directive or an initial set of clauses.

    Corrected a bug where local dynamic predicates would need a private scope 
    directive in order to allow clauses of the predicate to be retracted.

    Simplified compilation of dynamic and discontiguous predicate directives.

    Added new "logic" example implementing a translator from logic propositions 
    to conjunctive normal form.

    Corrected a problem with wrong end-on-lines on some files.

    Added a shell script for easy integration of Logtalk with CIAO Prolog.


2.17.1 - June 7, 2004

    Added custom handling of specification of predicate exceptions in info/2 
    documenting directives when writing XML documenting files (declared as 
    "exceptions is [Cond1-Term1, Cond2-Term2, ...]"; each pair (Condi, Termi) 
    represents an error condition and its respective exception). 

    Changed debugger command "e" to print exception terms instead of exiting 
    Logtalk session.

    Corrected a compilation error with B-Prolog due to operator priorities.

    Corrected a possible problem with the redefinition of loaded entities that 
    define (possibly at runtime) dynamic predicates. All clauses for an entity 
    dynamic predicates are retracted before loading the new entity definition.

    Corrected a potential bug when pretty printing terms with variables in the 
    debugger and in the created XML documenting files.

    Added four more DCGs examples ("walker movements", "iterative shell command 
    parsing", "bill of materials", and "command language").
    
    New "puzzles" and "metainterpreters" examples.

    Added a mode bundle for the SubEthaEdit 2.x (MacOS X) text editor providing 
    syntax coloring for editing Logtalk source files. Optimized some of the 
    regular expressions in the syntax coloring files for the Kate/Kwrite and Vim 
    text editors.

    Removed predicate nth/3 from library entities listp, list, and difflist. 
    Replaced by the predicates nth0/3 and nth1/3. Added new predicates nth1/4 
    and nth0/4.

    Updated the config file for Quintus Prolog to make use of the "files" 
    library.

    Added experimental implementations for some Prolog compilers of the library 
    portable protocol for operating system access (systemp.lgt). See the file 
    library/experimental/NOTES for details.


2.17.0 - April 26, 2004

    Added built-in debugging support implemented thro