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Logtalk - Object oriented extension to Prolog
Release 2.22.3

Copyright (c) 1998-2004 Paulo Moura.  All Rights Reserved.
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This file contains detailed instruction for installing and configuring 
Logtalk.


1. LOGTALK INSTALLATION

Installing Logtalk is just a matter of decompressing the downloaded archive 
and copying the resulting directory to a suitable location.

The Logtalk directory can reside in any user accessible location. This 
location depends on the working environment and on the number of users.


* Installing for a single user:

In the case of a single user, the Logtalk directory may simply be copied to 
the user home directory. In alternative, assuming a user with administrative 
rights, the same setup described below for multiple users may be applied. 
This has the advantage of allowing the user to freely try and modify the 
provided examples, library, and configuration files with the option of, at 
any time, restoring the files to its original state by simply running one of 
the provided scripts.


* Installing for multiple users:

In the case of multiple users, the Logtalk directory can be copied to any 
location that its accessible by all the users (assuming that copying the 
Logtalk directory to each user home directory is, for some reason, not 
feasible or desired).

The "misc" sub-directory contains shell scripts for easy installation of 
Logtalk on Windows, Unix, and Unix-like operating systems (for details, 
see the misc/NOTES file). These scripts make all files read-only in order 
to avoid user tempering. However, Logtalk directories such as "library" 
or "examples" must be user-writable as compiling Logtalk source files 
generates intermediate Prolog files, which are written to the same location 
as the source files. In addition, it is convenient that directories such as 
"configs", "libpaths", and "xml" be user-writable in order to allow each 
user to customize Logtalk to its needs. Given that making directories 
world-writable is a security risk, one solution is to copy the directories 
that need to be user-writable to each user home directory. The "misc" sub-
directory contains shell scripts (named "cplgtdirs.*") which may be called 
by the end-users for making such copies. This is the preferred setup for a 
computer lab. When used with one of the Prolog compilers for which an 
integration script is provided on the "misc" directory, this setup allows 
end-users to independently customize default compilation options and 
library paths.


2. LOGTALK CONFIGURATION

2.1 Setting environment variables

You need to set two environment variables, LOGTALKHOME and LOGTALKUSER. The 
environment variable LOGTALKHOME should point to the Logtalk installation 
directory. The environment variable LOGTALKUSER should point to a directory 
in your home directory where you want to store the user-specific Logtalk files
(for example, ~/logtalk). Both environment variables may be set for all users 
by a user with administration privileges. The two environment variables can 
have the same value if you are the only Logtalk user on your computer and if 
you have full permissions to the Logtalk installation directory. In addition, 
you may want to add the Logtalk sub-directory "xml", which contains useful 
scripts for processing XML documenting files, to your execution path.

* Unix and Unix-like systems:

If you use a csh shell, add the following line to your ~/.cshrc file:

	setenv LOGTALKHOME /your/logtalk/installation/directory
	setenv LOGTALKUSER $HOME/logtalk
	setenv PATH $PATH:$LOGTALKUSER/xml:$LOGTALKHOME/misc

If you use a bash shell, add the following lines to your ~/.profile file:

	LOGTALKHOME=/your/logtalk/installation/directory
	LOGTALKUSER=$HOME/logtalk
	PATH=$PATH:$LOGTALKUSER/xml:$LOGTALKHOME/misc
	export PATH LOGTALKHOME LOGTALKUSER

When using the provided shell script for installing Logtalk, a symbolic link 
to the Logtalk installation directory is automatically created. The link is 
named "logtalk". In this case, you may use this symbolic link to define the 
environment variable in order to avoid breaking it when upgrading Logtalk.

* Windows systems:

In Windows 95/98/ME, environment variables are defined in the "autoexec.bat" 
file (you will need to reboot after editing the file):

	SET LOGTALKHOME=C:\your\installation\folder\
	SET LOGTALKUSER=%HOMEPATH%\logtalk

In Windows 2000/XP, environment variables are defined using the System 
properties control panel (if you are a system administrator, you should use 
the JScript install script provided in the "misc" sub-directory; this script 
sets the LOGTALKHOME environment variable for all users and also sets the 
LOGTALKUSER environment variable for the administrator user running the 
script).


2.2 Setting library paths

In Logtalk, a library is simply a directory containing source files. Library 
paths can be declared using a dynamic predicate. This allows compiling and 
loading of libraries and library files to be performed without worries about 
library paths. In the "$LOGTALKUSER/libpaths" directory you will find a sample 
file which, when loaded, defines the library paths for the Logtalk standard 
library and for all the supplied examples. This file may need to be edited to 
match your Logtalk installation and your Prolog compiler and operating-system 
requirements. For more details, see the file "$LOGTALKUSER/libpaths/NOTES".


2.3 Customizing Prolog configuration files

Logtalk interfaces with a specific Prolog compiler via a configuration file 
that can be found on the "$LOGTALKUSER/configs" directory. These configuration 
files can be customized by changing the values of the default flags and 
compiler options which are used by Logtalk when compiling source files. For 
a full description of these default flags and compiler options, consult the 
"Running and debugging Logtalk programs" section of the User Manual. Some of 
the default flags that you may want to change are: "portability", "altdirs", 
"underscore_vars", "startup_message", "smart_compilation", and the set of 
documentation-related flags ("xml", "xsl", "xmlspec", and "doctype"). Be sure 
to read the "$LOGTALKUSER/configs/NOTES" file for Prolog specific notes; some 
Prolog compilers do not support the whole range of compilation flags.  


2.4 Customizing documentation processing scripts and supporting files

Logtalk provides, in the "$LOGTALKUSER/xml" directory, a set of shell scripts, 
CSS and XSLT style-sheets, and DTD and XML Schema files for processing the XML 
documenting files that are automatically generated when you compile source 
files. You may want to customize these scripts and their supporting files to 
modify the layout or style of the resulting PDF/(X)HTML files or to write new 
scripts and transformations to generate other formats. For more details, see 
the file "$LOGTALKUSER/xml/NOTES".


CREATING NEW PROLOG TOP-LEVELS FOR AUTOMATIC LOADING OF LOGTALK

Most Prolog compilers allows the user to define an initialization file that 
is automatically consulted at startup. This initialization file may contain 
directives for loading other files, such as the Logtalk configuration file 
and the Logtalk compiler. The "misc" sub-directory contains several scripts 
for automating the creation of these initialization files for some Prolog 
compilers. In addition, be sure to read the "configs/NOTES" file notes on the 
Prolog compilers that you intend to use.