root/tags/lgt2240/RELEASE_NOTES

=================================================================
Logtalk - Object oriented extension to Prolog
Release 2.24.0

Copyright (c) 1998-2005 Paulo Moura.  All Rights Reserved.
=================================================================


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


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 showstopper 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 autocomplete 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-stardard 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 through the definition of a 
    new pseudo-object named "debugger". Added "debug" compiler option. Renamed 
    library entities "debuggerp" and "debugger" to, respectively, "event_dbgp" 
    and "event_dbg".

    Improved installation instructions for multi-user environments. Added 
    a shell script for installing Logtalk in Unix and Unix-like operating 
    systems. Added a shell script for copying Logtalk xml, examples, and 
    library directories to the user home directory.

    Added a logtalk.spec file for building Linux RPMs from sources.

    Added a set of shell scripts for easy integration of Logtalk with ECLiPSe, 
    GNU Prolog, Qu-Prolog, SICStus Prolog, SWI-Prolog, and YAP.

    Corrected bug in the definition of the pseudo-object "user" that resulted 
    in mixed up metapredicate and type predicate properties.

    Removed config files for outdated versions of Qu-Prolog, SWI-Prolog, ECLiPSe,
    K-Prolog, CIAO, YAP, Amzi! Prolog, LPA Win-Prolog, SICStus Prolog, and XSB.


2.16.2 - April 2, 2004

    Corrected a bug in the library category monitor (file library/monitor.lgt) 
    that prevents its compilation.

    Changed the possible values of the read-only flag startup_message (defined 
    in the config files) to "flags" (print banner and flag values), "banner" 
    (print only the banner), and "none" (do not print neither the banner nor the 
    flag values). Default value is "flags".

    Updated the "errors" example to illustrate the error messages thrown when 
    trying to redefine Logtalk built-in control constructs.

    Corrected a small problem with the Logtalk language specification file for 
    Apple's Xcode IDE.

    Added preliminary support for syntax coloring using the Windows text editor 
    Crimson Editor.


2.16.1 - March 23, 2004

    The local built-in method parameter/2 can now be used inside categories 
    (but please read the warnings about such practice on the user manual).

    Updated the Logtalk compiler to report an error when the user tries to 
    redefine a message sending or external call control construct inside an 
    object or category.

    Corrected a bug in the compilation of metacalls whose meta-arguments are 
    variables.

    Removed references to file sax.jar from the scripts used to convert XML 
    documenting files into (X)HTML. Updated scripts html.sh, htmlnt.cmd, and 
    htmldos.bat to use XT 20020426a or later version.

    Improved syntax coloring accuracy of built-in predicates and methods for 
    the SubEthaEdit text editor.

    Updated config file for Qu-Prolog 6.4.


2.16.0 - March 3, 2004

    Logtalk is now distributed under the Artistic License 2.0.

    Operators declared inside an entity are now local to the entity, not 
    affecting the global operator table (complying with the Logtalk language 
    specification). Input and output of terms from inside objects and 
    categories now work as expected in the presence of local operator 
    declarations. Added a new example named "operators".

    Updated built-in method predicate_property/2 for returning metapredicate/1 
    properties for both Logtalk and Prolog metapredicates.

    Added support for calls to non-ISO Prolog standard built-in metapredicates 
    inside objects and categories. Added support for the declaration of non-ISO 
    Prolog standard metapredicates in the config files.

    Small change to the way the Logtalk compiler reports the compilation of
    entities. Small optimizations to the compilation of Logtalk source files.

    Corrected a bug where calls to Logtalk built-in predicates would be 
    reported as non-portable when the value of compiler option portability is 
    set to warning.

    New config file for Qu-Prolog 6.4 (see the configs/NOTES file for details).

    Corrected a problem with the syntax coloring of quoted atoms and strings 
    in the SubEthaEdit text editor. Added more accurate syntax highlight for
    built-in methods and built-in predicates.

    Updated the syntax coloring configuration files for all supported text 
    editors to recognize the file extension used by the config files.


2.15.6 - February 9, 2004

    Added "xmlspec" compiler option in order to specify the extension (dtd 
    or xsd) of the file describing the XML documenting files specification.

    Renamed compiler option "named_anonymous_vars" to the more appropriated 
    name "underscore_vars". Changed possible option values to "dont_care" and 
    "singletons" (default).

    Added XSLT file for converting XML documenting files to XHTML 1.0 Strict 
    files. Set the default encoding of all XSLT files to UTF-8.

    Added syntax coloring support for the KDE Kate and Kwrite text editors.

    Improved syntax coloring configuration files for VIM, jEdit, NEdit, 
    SubEthaEdit, and Emacs text editors.

    Removed outdated support for MacOS X Project Builder and added support 
    for the new MacOS X Xcode developer tool.

    Corrected bug in the built-in predicate current_logtalk_flag/2 that 
    prevented some flag values from being returned after using the built-in 
    predicate set_logtalk_flag/2.

    Corrected bug in the shapes example (wrong placement of the declaration 
    of the predicate side/1).


2.15.5 - December 30, 2003

    Make operator ^^/1 right-associative for consistency with remaining 
    operator declarations.

    Added file BIBLIOGRAPHY containing a list of Logtalk publications in 
    BibTeX format.

    Added a font-lock file for Emacs providing syntax coloring for editing 
    Logtalk source files.

    Added an implementation of the Smalltalk dependent mechanism to the 
    standard Logtalk library.

    Updated the config file for ECLiPSe 5.4~5.7 with missing ISO Prolog 
    predicate definitions needed for successful compilation of all entities 
    in the Logtalk standard library.

    Updated manual pages to comply with XHTML 1.0 Strict and to provide 
    better navigation.


2.15.4 - July 9, 2003

    Corrected a spurious backtracking bug in the DCG rule translator. Added 
    two more examples of DCGs.

    New config file for XSB 2.6. Updated Logtalk compiler to compile cleanly 
    under XSB after applying the patch described in configs/NOTES.

    Updated SWI-Prolog config file to hide compiled entity predicates (requires 
    SWI-Prolog 5.2.3 or later version). New optional file configs/swihook.pl 
    contains hook code that allows Logtalk entities to be compiled and loaded 
    using SWI-Prolog load_files/2 and consult/1 predicates.

    Syntax definition file for the Hydra 1.1 (MacOS X) text editor providing 
    syntax coloring for editing Logtalk source files.

    Updated syntax coloring files for jEdit, NEdit, Vim, and TextPad in order 
    to recognize character code constants (0'x) and the DCG operator -->/2.


2.15.3 - June 27, 2003

    Updated experimental support for DCG rules to prevent over-simplification 
    of unification goals in the compilation of rules to clauses. Push-back 
    lists can now be used on rule heads.

    The compilation mode of an entity (static/dynamic) is now stored in the 
    corresponding entity table (implying recompilation of all entities).

    Updated GNU Prolog config file to hide compiled entity predicates.

    Updated SWI-Prolog config file for better integration of Logtalk with 
    this compiler.


2.15.2 - April 2, 2003

    Experimental support for DCG rules inside categories and objects. Added 
    built-in methods phrase/2 and phrase/3.

    Updated GNU Prolog config file to not hide compiled entity predicates in 
    order to avoid incompatibilities with dynamic entities.


2.15.1 - March 8, 2003

    New example, msglog, of using events and monitors to record, replay, and 
    print user messages.

    Corrected a typo on the jEdit templates that resulted in syntax errors.
    Corrected wrong year format in info/1 directive in all entity templates.
    Added missing version info key to jEdit prototype template.

    Corrected documentation of built-in local methods self/1 and sender/1.
    Updated documentation of built-in local methods parameter/2 and this/1.


2.15.0 - February 5, 2003

    Changed "authors" key in info/1 directive to "author".

    Corrected documentation of built-in local method this/1.

    New geometric shapes example implemented in two versions, one 
    prototype-based and the other one class-based.

    Improved support for jEdit text editor by adding a set of programming 
    templates for use with the editor Templates plug-in.

    Added basic support for syntax highlighting and programming templates 
    for MacOS X Project builder.


2.14.7 - January 10, 2003

    Corrected a bug in the built-in methods asserta/1 and assertz/1 when 
    asserting predicate rules.

    The built-in predicates logtalk_compile/1-2 and logtalk_load/1-2 now 
    accept both an entity (an atom) or a list of entities (a list of atoms).

    Optimized the code generated when compiling or asserting clauses for 
    dynamic predicates.

    Optimized protected inheritance performance on some Prolog compilers.


2.14.6 - December 31, 2002

    Corrected a bug where the opening directive of an object that, 
    simultaneously, implements a protocol, imports a categoty, instantiates 
    a class, and specializes a superclass, will not be recognized.


2.14.5 - December 20, 2002

    Simplified dynamic table of predicate declarations by removing two 
    redundant arguments.
    
    Corrected a bug where sending messages such as true/0 or !/0 to an 
    unknown object succeeded instead of throwing the correct exception.

    Simplified the code used to generate links in the lgtpdfa4.xsl and 
    lgtpdfus.xsl XSLT files.


2.14.4 - November 5, 2002

    Removed definition of depracated built-in predicate logtalk_version/3.

    Show flag names when printing at startup the default flag values.

    Small change to messages printed on console with smart compilation of 
    source files turned on.

    Updated YAP 4.3.x config file to use the YAP "system" library to access 
    the operating system for time, date, and file properties (enabling smart 
    source code compilation).

    Updated the lgtpdfa4.xsl and lgtpdfus.xsl XSLT files to workaround a bug 
    in the PassiveTeX 1.21 XSL:FO processor.


2.14.3 - Sptember 16, 2002

    New compiler option, doctype, to set the doctype reference (if any) 
    in the XML documenting files. Default value is "local" for backward 
    compatibility. Updated the user manual section on compiler options.

    The Logtalk built-in predicate logtalk_version/3 should be considered 
    deprecated (use current_logtalk_flag/3 instead). All references to this 
    predicate have been removed from the manuals.

    Updated the jEdit syntax coloring config file for the new jEdit 4.1 
    version.

    Updated the lgtpdfa4.xsl and lgtpdfus.xsl XSLT files for compatibility 
    with the XSL:FO processors Apache FOP 0.20.4, PassiveTeX, and RenderX 
    and with the XSL W3C Recommendation of October 15, 2001. Updated the 
    pdf.bat and pdf.sh scripts to reference the latest version of the 
    Apache FOP processor (0.20.4).

    Changed the shell scripts html.sh and pdf.sh for compatibility with the 
    sh, bash, and zsh shells.


2.14.2 - August 26, 2002

    Calls to built-in method parameter/2 are now compiled inline, improving 
    call performance.

    Updated Logtalk compiler to clean temporary compilation predicates after 
    compiling an entity instead of only before compilation.

    Updated YAP 4.3.x config file for better Logtalk integration by hiding 
    all internal compiler, runtime, and compiled entities static predicates.

    Updated GNU Prolog config file for better Logtalk integration by hiding 
    all internal compiler, runtime, and compiled entities predicates.

    Updated the XSLT conversion scripts lgtxml.xsl and lgthtml.xsl to correct 
    some HTML conformance errors in the generated pages.

    Corrected some XHTML conformance errors in the manual pages.


2.14.1 - July 31, 2002

    New Windows NT script and updated Unix shell script for batch converting 
    XML documenting files to HTML. Both scripts also generate an index.html 
    file containing links to all converted XML documenting files.

    Corrected wrong XHTML DOCTYPE declaration in manual pages.


2.14.0 - July 26, 2002

    Renamed all compiler and runtime internal predicates and all auxiliary 
    predicates in the config files to start with a "$" character.
    
    New compiler option, code_prefix, to set a prefix for all Prolog code 
    functors generated by Logtalk when compiling entities. Default is ''.

    New compiler option, named_anonymous_vars, that instructs the compiler to 
    interpret variables that start with an underscore as anonymous variables 
    (and to not report them as singleton variables). Default value is "off".

    Directive info/2 was wrongly declared as a entity directive instead of a 
    predicate directive.

    Converted all manual pages to XHTML 1.0 format. Corrected a wrong link in 
    the reference manual. Replaced GIF images by PNG versions.

    Updated BProlog 6.x config file to workaround the new 6.2 built-in 
    predicate ::/2 that conflicts with the same named Logtalk message sending 
    operator.

    Removed call to the obsolete built-in predicate nodbgcomp/0 from all 
    ECLiPSe config files.


2.13.0 - June 15, 2002

    Logtalk now outputs Prolog code using write_canonical/2 instead of 
    write_term/3. Goals are better portability of the generated Prolog files 
    and avoid issues with clauses with long bodies for Prolog compilers that 
    use a term print depth limit to prevent problems with cyclic terms.

    Added report of default flag values at Logtalk startup.

    Logtalk now prints a warning when redefining parametric objects.

    Removed need of an abort/0 predicate from the Logtalk debugger example.
    Removed any definition of this predicate from the config files.

    Added missing definitions for some ISO built-in predicates to the Amzi! 
    Prolog 6.2.2 config file.


2.12.0 - May 25, 2002

    New read-only Logtalk flag "version". Corrected exception term generated 
    when trying to modify a read-only flag using the set_logtalk_flag/2 
    built-in predicate.

    Updated config file for OpenProlog 1.1b5.

    New config file for ECLiPSe 5.4.

    Renamed config files for CIAO 1.7 (beta of 1.8) to "ciao_aux18.config" 
    and "ciao18.config".

    Updated config file for Amzi! Prolog 6.2.2.

    New example of using some of the built-in database handling methods 
    (dynpred).

    Syntax configuration files for jEdit 4.0, VIM 6.1, NEdit 5.2, and 
    TextPad 4.5 text editors providing syntax highlighting for editing 
    Logtalk source files.


2.11.0 - April 22, 2002

    Added a "smart compilation" feature to the Logtalk compiler, controlled 
    by a "smart_compilation" flag. Only available in Prolog compilers that 
    provide access to file modification dates.

    Added a "startup_message" flag to control printing of the Logtalk banner 
    at startup.

    Reworked Logtalk pre-processor compilation and loading reports. Compiler 
    option "report" now togles between normal reporting (as specified by the 
    other flags) and silent compilation/loading of source files.


2.10.0 - April 5, 2002

    Scope of object asserted predicates for which there is no declaration is 
    now a function of the context instead of always being declared public. 
    Asserting in this, the predicate is declared private, asserting in self, 
    the predicate is declared protected, otherwise the predicate is declared 
    public.

    Throw an error if a category contains clauses for dynamic predicates.

    Updated documentation on categories and built-in methods for database 
    handling.

    Retracting all clauses for a dynamic predicate from an object now allows 
    an inherited definition to be called when sending the corresponding 
    message. In previous versions the message just failed.

    Added missing entries for the built-in predicates current_logtalk_flag/2 
    and set_logtalk_flag/2 to the Logtalk compiler built-in predicates table.

    Updated config file for Amzi! Prolog 6.1.74.

    Updated notes on patching XSB to work with Logtalk.


2.9.3 - February 9, 2002

    New current_logtalk_flag/2 and set_logtalk_flag/2 built-in predicates.

    Updated documentation on new built-in predicates.

    Renamed SWI-Prolog config file swi330.config to swi.config.

    Renamed config file predicate lgt_default_compiler_option/2 to lgt_flag/2.

    New XSL stylesheets and shell scripts to convert Logtalk XML entity 
    documenting files to PDF format using XSL Formating Objects.


2.9.2 - January 4, 2002

    The Logtalk compiler can now print a warning when compiling source files 
    that use non-ISO defined built-in predicates using a new portability/1 
    compiler option. Updated the relevant sections of the user manual and the 
    errors example.

    Corrected a compiler bug where the entity relation tables only recorded 
    the last entry per entity relation type.
    
    Updated config file for CIAO 1.7#162.


2.9.1 - December 5, 2001

    Logtalk compiler now prints a warning when redefining or replacing an
    existing entity.

    Corrected a compiler bug in the error checking code for the info/1 
    and info/2 directives.

    Changed the order of object loading in the "mi" example to avoid 
    suporious warning messages.
    
    Added a new problem ("bridge") to the "searching" example. Improved 
    "performance" monitor to give correct reports on alternative solutions. 
    Corrected a bug in the "water jug" state space example.


2.9.0 - October 22, 2001

    Added config files for CIAO Prolog 1.7p115 and B-Prolog 6.0.

    Compiling and loading an entity that contains references to unknown 
    entities (by default) prints a warning. Updated user and reference 
    manuals.

    Rewrited all the compiler warning/error code and output messages.

    Changed compiled code functors postfixes from "_sdcl" and "_sdef" to 
    "_idcl" and "_idef" (implies recompilation of all objects, protocols, 
    and categories).

    Changed all occurrences and references to the term "entity_scope" to 
    "scope".

    Removed some redundant productions from the Logtalk grammar.

    Updated documentation on the xml directory. Renamed some of the .xsl 
    files. Added sample scripts to batch convert .xml files to .html files.
    
    Added a new loader utility file, all.loader, to load all library files 
    loaded by the other loader files.

    Started work on documenting the Logtalk pre-processor/compiler source 
    file.

    New "errors" example. Updated the "inheritance" example.


2.8.4 - March 9, 2001

    Updated config files for BinProlog 8.0, K-Prolog 5.01, XSB 2.3, and
    Amzi! Prolog 4.103~5.0.
    
    New config file for Amzi! Prolog 6.1 beta.

    Corrected an incomplete entity definition in the Logtalk XML DTD.
    Rewrite the Logtalk XSLT files for improved compatibility with XSLT 
    processors regarding handling of whitespace.

    A first cut of a XML Schema for the Logtalk XML documentation files
    (file xml/logtalk.xsd).

    Small improvements to the documentation.


2.8.3 - November 21, 2000

    Corrected a bug where sending a message for a built-in method to an 
    unknown object fails instead of generating the