================================================================ Logtalk - Open source object-oriented logic programming language Release 2.30.8 Copyright (c) 1998-2007 Paulo Moura. All Rights Reserved. ================================================================ RELEASE NOTES ============= 2.30.8 - November 9, 2007 Fixed bug in the compilation of synchronized predicates that breaks Logtalk on single-threaded Prolog compilers. 2.30.7 - November 5, 2007 Updated the multi-threading built-in predicates threaded_notify/1 and threaded_wait/1 to accept lists of notifications. Added a new read-only compiler flag, "context_switching_calls", allowing context switching calls to be disabled (they are enabled by default). Updated the B-Prolog config file to recognize eager_consume/1 directives. Updated the XSB config file to recognize use_subsumptive_tabling/1, use_variant_tabling/1, index/1, thread_private/1, and thread_shared/1 directives. Updated the YAP config file to recognize thread_local/1 directives. Updated the SICStus Prolog config files to recognize volatile/1 directives. Updated the SWI-Prolog config file to recognize thread_local/1, index/1, and hash/1 directives. Changed the backup directory names generated by the "cplgtdirs.*" shell scripts to not include whitespace characters. Updated the "xsbmtlgt.sh" integration script to start XSB-MT using the new command-line option "--shared_predicates" (requires current XSB CVS version). Updated the Windows GUI installer to support running Logtalk with XSB-MT. Added a multi-threading example, "barriers", of barrier synchronization. Updated the "functions" example sample queries for compatibility with the ISO Prolog standard regarding representation of float numbers. Added a workaround for a parsing bug in XSB while compiling the "sicstus" example. 2.30.6 - October 21, 2007 Replaced calls to the proprietary current_thread/2 predicate in the Logtalk runtime by calls to the thread_property/2 predicate as per the ISO DTR on multi-threading predicates. Added a goal_expansion/2 clause to the SWI-Prolog config file to automatically switch between the current_thread/2 and thread_property/2 predicates depending on availability. Changed handling of the encoding/1 directive by the Logtalk compiler in order to improve compatibility with YAP and SICStus Prolog. Removed from the config files the now obsolete '$lgt_set_stream_encoding'/2 predicate definition. Renamed the compiler option "supports_encoding_dir" to "encoding_directive" and changed its possible values to "unsupported", "full" (used in both Logtalk source files and compiler generated Prolog files), and "source" (used only in Logtalk source files). Renamed compiler option "underscore_vars" to "underscore_variables". Renamed compiler option "supports_break_predicate" to "break_predicate". Improved the performance of recursive predicate definitions synchronized by mutexes. Explicitly create all mutexes used by an entity at load time for compatibility with XSB. Several changes to multi-threading support in order to improve compatibility with current and forthcoming versions of YAP, SWI-Prolog, and XSB. Updated the Logtalk compiler for compatibility with both logical and immediate update semantics when compiling synchronized predicates. Updated the meta-predicate compilation sanity checks to verify the existence of the minimum number of normal arguments in a clause head required by the closure of maximum arity. Added a workaround for the lack of built-in support for character unbuffered input when using the Logtalk built-in debugger to the config files of ALS Prolog, B-Prolog, Ciao, CxProlog, IF/Prolog, JIProlog, Prolog II+, SICStus Prolog, XSB, and YAP. Thanks to Parker Jones for the bug report. Updated the YAP config file to auto-detect working Unicode support when setting the "encoding_directive" compiler option. Updated the XSB config file to auto-detect multi-threading support when setting the "threads" compiler option. Added an integration script (xsbmtlgt.sh) and supporting files for the multi-threaded version of XSB (requires current development version, available from the XSB CVS server). Added a MacPorts portfile for building MacOS X installer packages. Added a BOM to the "babel.lgt" UTF-8 file in the "encodings" example in order to improve compatibility with SICStus Prolog. Updated the library object "random" by replacing the synchronized/0 directive by a synchronized/1 directive listing only the predicates that modify the random number seed. Added syntax coloring support for the GtkSourceView 2.x text widget (used e.g. on the Gnome's Gedit text editor and on the MonoDevelop IDE). Removed syntax coloring for the obsolete atomic/1 predicate directive from the support files of Source-highlight, Emacs, SubEthaEdit, jEdit, and Kate. Optimized the regular expressions used in most syntax coloring configuration files of supported text editors. 2.30.5 - September 19, 2007 Added new multi-threading built-in predicates threaded_call/2, threaded_once/2, threaded_exit/2, and threaded_peek/2. These new predicates support the use of threaded call identifier tags in order to link specific threaded_call/2 and threaded_once/2 calls to specific threaded_exit/2 and threaded_peek/2 calls. Extended the "nondet" example in order to illustrate the new functionality. Changed the implementation of the built-in predicate threaded_exit/1 in order to avoid blocking when its argument is subsumed by the argument of the corresponding threaded_call/1 call instead of being a variant. Updated the Logtalk compiler to encapsulate resource errors inside error/2 exception terms (as specified in the ISO Prolog core standard). Corrected a bug in the library object "lgtunit" (wrong arity on two failed_test/2 predicate calls). Corrected two problems with the "testing" example: a wrong call on the object "dyn_tests" and a missing entry in the "libpaths.pl" file. Removed two pointless dynamic predicate directives in the "buffer" example. Improved documentation of multi-threading programming and predicate properties. Corrected the reference manual page describing the threaded/0 directive. Simplified installation scripts by moving shared distribution cleaning code into the "cleandist.sh" script. Updated the "install.sh" script to set the installation prefix to "/usr" on Debian systems. Updated the Linux RPM spec file in order to clean the building directory after the package creation. 2.30.4 - August 22, 2007 Allow the argument of {}/1 calls to be a variable at compile time. Updated the Qu-Prolog config file to match and require version 8.1 and added a "qplgt" integration script. Updated the XSB config file to match and require version 3.1 and to take advantage of the compiler option optimize/1 when loading Logtalk generated Prolog intermediate files. Added a new library object, "lgtunit", providing preliminary support for writing and running unit tests. Added a new example, "testing", defining sample unit tests. Added a new multi-threading example, "threads/tak", implementing the Takeuchi function (recursive arithmetic). Updated the "threads/philosophers" example to use notifications instead of a dynamic predicate for representing chopstick availability. Added an alternative implementation using a parametric object. Improved example documentation. Updated the "benchmarks" example to allow comparisons between calls to imported category predicates and calls to local object predicates. Updated Emacs support in order to fix problems with the syntax-coloring of some Logtalk built-in predicates and applied a patch contributed by Nicolas Pelletier to workaround a compatibility problem with XEmacs. Updated jEdit support in order to fix a problem with the syntax-coloring of the :/1 control construct. 2.30.3 - July 9, 2007 Updated the multi-threading built-in predicate threaded/1 to support both conjunctions of goals (akin to and-parallelism) and disjunctions of goals (akin to or-parallelism) as an argument. Removed the experimental threaded_race/1 multi-threading built-in predicate (its or-parallelism functionality is subsumed by the updated threaded/1 predicate). Corrected a bug in the implementation of the multi-threading built-in predicate threaded_exit/1 when there are more than one thread running the same non-deterministic goal (the fix ensures that all alternative solutions per threaded_exit/1 call come from the same computing thread). Thanks to Paul Crocker for the suggested bug fix solution. Updated the sample queries in the "threads/buffer"/SCRIPT.txt" file to match the updated entities in the example. Updated the "threads/functions" example to use the new version of the threaded/1 multi-threading built-in predicate. 2.30.2 - June 24, 2007 Updated the Logtalk compiler to throw a compilation error when duplicated or conflicting predicate scope directives are found. Updated the Logtalk compiler to correct a cosmetic glitch when reporting compilation errors. Updated the Logtalk compiler to check for mismatches between the argument of this/1 calls and the parametric object identifier. Corrected a bug in the implementation of the multi-threading built-in predicate threaded_ignore/1. Revamped the "threads/buffer" example to support setting the buffer maximum number of items. Added a new DCG example, "dcgs/morse.lgt", for parsing messages in Morse code. Extended the "parametric" example to illustrate a solution for dealing with inheritance when defining "setter" predicates/methods that return updated object identifiers. 2.30.1 - June 12, 2007 Added a new, experimental control construct, :/1, for calling imported category predicates without using message sending mechanisms. Added preliminary support for static binding when calling imported category using the new :/1 control construct for categories compiled and loaded using the compiler option "reload(skip)". Added a new control construct, < "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 /. 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 () 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 (). 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 () 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 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 category, 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 deprecated 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 - September 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 toggles 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 style-sheets 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 spurious 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. Rewritten 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 expected exception. Put some occurrences of atoms public, mode, and type between ()'s to avoid compilation errors in BinProlog 8.0 and other Prolog compilers that declare these atoms as operators. Corrected the definition of the state space of the "Missionaries and Cannibals" problem in the "searching" example that resulted in some wrong solutions. 2.8.2 - November 5, 2000 New .xsl file to convert .xml files to TeXML files. Fixed a problem with explicit compilation options being correctly parsed but not processed. Corrected a bug regarding default init options definition for the points, polygons, and bricks examples. Updated category initialization in roots example. 2.8.1 - October 28, 2000 New config file for K-Prolog 5.0. Improved compiler error detection and reporting of invalid directives and clauses. Corrected a problem with some Prolog compilers where compiling a file containing syntax errors may not close the file after the errors are reported. Many small improvements to all documentation. Small improvements to the .xsl files and to the output of .xml files. 2.8.0 - October 1, 2000 I have found just a few days ago that I have uploaded to the Logtalk web server a development version of Logtalk 2.7.0 instead of the final one! To avoid confusions I decided to release a new version. Changed implementation of the logtalk_compile/1-2 and logtalk_load/1-2 predicates to only accept a list of entities instead of either an entity or a list of entities, simplifying and improving the performance of these predicates. Improved error reporting for the logtalk_compile/1 and logtalk_load/1 predicates. Updated relevant sessions in the user and reference manuals. Simplified the implementation of the following predicates, by sharing the error checking code with the corresponding extended versions: implements_protocol/2, imports_category/2, instantiates_class/2, specializes_class/2, extends_protocol/2, and extends_object/2. Completed some missing library file dependencies documentation in some examples. New version of the QUICK_START help file. Updated tutorial. 2.7.0 - August 24, 2000 First release of the Logtalk standard library of objects, protocols and categories. Rewritten all examples to use the new Logtalk standard library. New logtalk_load/2 and logtalk_compile/2 Logtalk built-in predicates, accepting a list of compiler options. See the User and Reference Manuals for details. New XSLT file for viewing .xml files in Microsoft Internet Explorer 5.5 for Windows after installing the latest Microsoft XML Parser Preview Release. Small improvements in all XSLT files. Starting with this version all config files need to provide a definition for the compare/3 predicate if it is not built-in in the corresponding Prolog compiler. Also, default Logtalk compiler options are now also set in the config files using the lgt_default_compiler_option/2 predicate. Updated config file for CIAO 1.6p1. See the configs/NOTES file for details. 2.6.2 - July 4, 2000 Improved performance and error checking for the built-in predicates create_object/4, create_protocol/3 and create_category/4. Updated config file for BinProlog 7.83. Many small updates to all documentation. New PDF versions of the documentation formated for printing (with page numbers, table of contents and index)are now available in both A4 and US letter formats. 2.6.1 - May 5, 2000 Modified the structure of the automatically generated XML documenting files to improve XSL translation performance. Added a new, more standard compliant, XSL file to generate HTML files and renamed the old one to ie5.xsl. See the xml/NOTES file for details. Corrected an error in the logtalk.css CSS file. Modified the definitions of predicates lgt_file_extension/2 and lgt_file_name/2 in all config files. Updated all the user manual sessions related to automatic documentation. Updated all HTML documentation for future XHTML 1.0 conformance. Start adding documenting directives to most examples. 2.6.0 - April 27, 2000 Added support for documentation of objects, protocols, and categories, using automatic generation of XML files. Added info/1 and info/2 directives for documenting objects, protocols, categories, and predicates. Added definition of documentation file name extension and default file names for the DTD and XSL files to the config files. Improved error checking for the built-in predicates create_object/4, create_protocol/3 and create_category/4 to also detect invalid entity identifiers. Updated the user and reference manuals to describe the new automatic documenting features. Updated all HTML documentation to conform to HTML 4.01 strict standard. Corrected some wrong cross-reference links and titles in the reference and user manuals HTML pages. PDF versions of the manuals and tutorial are now available in both A4 and US letter formats. Corrected two errors in the searching example, one in the definition of the farmer problem state space and the other when backtracking over performance reports. 2.5.2 - March 7, 2000 Updated manuals to clarify some limitations of declaring and defining dynamic predicates inside categories and documented a way of using the built-in local method this/1 to access object parameters. Removed references to parametric categories from the Logtalk documentation (at runtime we can only access object parameters, not category parameters). Corrected two wrong declarations of built-in methods (forall/2 and retractall/1) in the Logtalk pre-processor. Corrected bug where predicates declared in dynamic entities may have a "static" instead of a "dynamic" property. Corrected a bug in category compilation that prevented a dynamic category from being abolished. Speedup predicate definition lookups for categories. 2.5.1 - February 18, 2000 Two new examples: birds, a bird identification expert system adopted (with permission) from an Amzi example, and viewpoints, a set of prototypes showing how to do property sharing and value sharing in Logtalk. Renamed config file yap421.config to yap430.config to match the name of the new YAP 4.3.0 public release (named 4.2.1 while on beta testing). Partial config file for Trinc Prolog R3. 2.5.0 - December 29, 1999 The Logtalk pre-processor now accepts arbitrary clauses and directives to appear in a file before an opening entity directive. The clauses and directives are added unchanged to the compiled file. Improved performance for all kinds of message sending. Two new examples: reflection, showing how to implement a simple class-based reflective system, and symdiff, showing how to use parametric objects to implement symbolic expression differentiation and simplification. Updated config file for the beta 8 release of SWI-Prolog 3.3.0. 2.4.0 - December 1, 1999 Logtalk is now an Open Source project, available under Perl's Artistic license. Two new examples: instmethods, illustrating the use of instance defined methods, and classvars, showing how to implement class variables. Updated Logtalk grammar to explicitly allow for user-defined types in mode/2 directives. New config files for SWI-Prolog 3.3.0, SICStus Prolog 3.8 and CIAO Prolog 1.4p0 (incomplete). Updated config file for B-Prolog 4.0. Updated config file for GNU Prolog to use the new call_with_args() built-in predicate added in version 1.1.0. Updated config file for YAP Prolog to use the new call_with_args() built-in predicate added in version 4.2.1. 2.3.1 - September 22, 1999 Logtalk pre-processor updated to only report one warning per redefined Logtalk or Prolog built-in predicate. Changed some occurrences of atom "public" to "(public)" in compiler/logtalk.pl file to avoid syntax errors in Prolog compilers (like BinProlog) that define "public" as an operator. Also put some terms between ()'s to avoid syntax errors with ALS Prolog 3.1 Update config file for ALS Prolog to work with version 3.1. Updated configs/NOTES file include a workaround to use Logtalk with XSB 2.0, some guidelines on how to write loader utility files for BinProlog 7.50, and a bug in ALS Prolog 3.1 that affects Logtalk. 2.3.0 - September 12, 1999 Metapredicate information is now stored with the other predicate properties, instead of being discarded after compiling the clauses of a metapredicate. Added predicate property metapredicate/1. It is now possible to assert clauses for dynamic metapredicates. Corrected a bug in the processing of metacalls in pseudo-object user. Corrected a bug in the implementation of private inheritance. Improved performance of protected inheritance. Corrected failure of processing initialization/1 and op/3 directives in create_object/4, create_category/4 and create_protocol/3 built-in predicates. Corrected a bug when calling private static category predicates from importing objects. Simplified code generated for categories. Rewrite code for the built-in method current_predicate/1 to avoid duplicated or wrong results when overriding predicate declarations and to ensure that all possible argument type errors are detected. Changed compilation of classes that do not instantiate any (meta)class in order to throw the correct exception when a message is sent to them. Changed compilation of root objects (that do not instantiate, specialize or extend other objects) so that calls to "super" (^^/1) fail (as they should) instead of generating a "predicate does not exist" error message. Changed implementation of "super" calls (^^/1) to avoid a potential endless loop problem when using these calls from the inheritance root object of a reflexive class-based systems. Pre-processor now checks for callable and object identifier errors. Runtime now checks for non-instantiated messages. Added new example (inheritance) about public, protected and private inheritance. Updated metapredicates, lo, kernel, and types examples. Most of the code in the last two examples is being updated to form the basis of an upcoming Logtalk standard library. Small changes in the pre-processor/runtime code for compatibility with ECLiPSe 4.2.2. Updated config files for this Prolog compiler. Rewrite some predicates in the config files for SWI-Prolog and LPA Mac & WIN Prologs for improved performance. New tutorial session about events and monitors. Updated documentation to match the changes made in this version. 2.2.0 - July 10, 1999 Implemented public, protected and private object inheritance, protocol implementation and category importation. New Logtalk built-in predicates instantiates_class/3, extends_object/3, extends_protocol/3, specializes_class/3, imports_category/3 and implements_protocol/3. The third argument returns the relation scope. Pre-processor now checks most directive errors. Changed ^^/1 (super call) implementation to only allow the use of a single predicate call for argument and to retain the original sender of the message (see the updated sicstus example). Fixed bug that prevented directives with a variable number of arguments (like dynamic(), public(), uses(), ...) being recognized. Changed definition of predicate read_term/3 in the configs files of Amzi!, Aquarius, Arity, Eclipse, IC, K, LPA Mac&WIN, Master and XSB to always instantiates the singleton variables list to the empty list. Needed to prevent backtracking problems in logtalk_load/1 and logtalk_compile/1 predicates. Removed choice-point in processing metacalls in predicate definitions. A banner with the Logtalk version is printed after loading the runtime/ pre-processor. Removed variables example. The category attributes is now part of the kernel example. Corrected some harmless syntax errors in directives in kernel/attributes.lgt, kernel/monitor.lgt and miscellaneous/queens.lgt. Changed name of blocks example to bricks and object "block" to "brick" in order to avoid problems with some Prolog compilers that use the atom "block" for operators or built-in predicates. 2.1.0 - May 11, 1999 Fixed some bugs in the definition of the pseudo-object user when sending the message predicate_property/2. Renamed config file for Calypso to GNU Prolog. New config file for LPA WinProlog 4.0. Corrected the omission in the documentation of the Logtalk grammar of the built_in entity property. New tutorial pages about building reflective class-based systems. Modified pre-processor to compile throw/1 as a control structure to ensure compatibility with the GNU-Prolog compiler. Modified pre-processor to ensure compatibility with Prolog compilers that use immediate update semantics instead of the ISO logical database update. Improved simplification of compiled object and category clauses. Rewrite and clean up pre-processor code for better compiler performance. Several updates to the examples files. Changed all example loader files to wrap the call to logtalk_load/1 inside an initialization/1 directive for ISO standard compliance. 2.0 GM - February 9, 1999 Removed some redundant choice-points that are being created when compiling Logtalk entities. Small compilation speed optimizations. Logtalk compiled files now contain the declarations for the message sending operators to ensure compatibility with some Prolog compilers. Changed the way Logtalk pre-processor writes directives to ensure compatibility with some Prolog compilers. Corrected a bug in the processing of the op/3 directive. Updated PrologII+ config file for version 4.5. Changed the definitions of catch/3 and throw/1 in the config files for LPA Prolog compilers. New config file for MasterProlog 4.1; removed config file for the old BIM Prolog 4.0. Corrected an error in the config file for OpenProlog in the definition of the write_term/3 predicate. Added a safer definition for write_term/3 predicate in the config files for Amzi, Aquarius, Arity, Eclipse, IC, K, LPA Mac, LPA Win, and XSB Prolog compilers. Added a QUICK_START file. 2.0 Beta 3 - February 1, 1999 Closed some encapsulation holes in the implementation of super calls. Changed Logtalk pre-processor to use write_term/3 instead of write/2 and writeq/2 to workaround some compatibility problems with some Prolog compilers. Changed mode operators priority and type to be compatible with the ISO standard. Modified definition of predicate read_term/3 in the config file for Amzi compiler to return the atom end_of_file instead of '!EOF' at the end of a file (this prevented Logtalk to complete compilation any file under this compiler). Improved detection of built-in predicates while compiling. Removed config file for wamcc. This compiler have been replaced by Calypso (developed by the same author). Updated K-Prolog config file for version 4.50. Improved documentation of template config file. Added SCRIPT files to the kernel and types examples. Updated Tutorial and User and Reference Manuals. New end user license. 2.0 Beta 2 - November 16, 1998 Built-ins logtalk_compile/1 and logtalk_load/1 updated to match the documentation regarding thrown errors and to accept a list of entities to compile/load. Modified the examples loader utility files to make only a call to logtalk_load/1 by using a list of entities. This should make it easy to modify these files for compilers that don't support arbitrary queries in a file. Logtalk runtime no longer tries to catch some of the errors thrown by ::/2. Added to all config files a Logtalk predicate to check if a file exists in the current working directory (used by the logtalk_load/1 and logtalk_compile/1 Logtalk built-in predicates). New configs files for the K-Prolog 4.14 and Calypso 1.0b6 Prolog compilers. Completed the config file for Open Prolog 1.03d38 (with the exception of lgt_current_date/3 that still have a dummy definition). Added a missing definition for Logtalk predicate forall/2 to the config file for Prolog II+ 4.4. Modified Logtalk pre-processor/runtime to avoid syntax errors when running on Open Prolog or Calypso and to remove some redundant choice-points that are being created when compiling categories and protocols. Modified some examples that use operators to avoid syntax errors in some Prolog compilers. Modified the implementation of the built-in method predicate_property/2 to avoid duplicate answers and to throw an instantiation error if the first argument is not bound. Modified definition of the pseudo-object user to hide Logtalk pre- processor predicates from the current_predicate/1 built-in method and to ensure that the predicate_property/2 built-in method returns Logtalk defined predicate properties for built-in Logtalk and Prolog predicates. Modified Prolog code generated by the pre-processor to further minimize possible conflicts with user defined predicates. Added a lgt_predicate_property/2 predicate to the config files to improve Logtalk portability. Updated Tutorial and User and Reference Manuals. 2.0 Beta 1 - October 18, 1998 Added basic support for implementation multi-inheritance. Logtalk pre-processor updated to try to detect misspelt local predicate calls. First public beta. 2.0 Alpha 1 - July, 1998 First release for registered users.