Rtcl - A Tcl Extension for Embedding the R Statistical Language
	---------------------------------------------------------------

DESCRIPTION
===========

The Rtcl extension embeds an interpreter for the R programming
language (see http://www.r-project.org) inside a Tcl interpreter. It
provides commands for evaluating R expressions, for importing their
values into Tcl, and for determining their type.


REQUIREMENTS
============

Rtcl requires the following software packages to be installed:

    1. Tcl, version 8.6 or newer
    2. R, version 3.4 or newer, built with shared libraries
    3. Typical R install with include files
	

INSTALLATION
============

Installation of Rtcl follows Tcl's usual configure/make/make install
pattern. A typical installation on Unix will look like:

    % tar xvzf Rtcl1.1.tar.gz
    % cd Rtcl1.1
    % ./configure
    % make
    % make test
    % su
    password:
    # make install
    # ^D
    %

The configure script accepts a number of options, including:

    --with-tcl=tclDir        Directory containing "tclConfig.sh"
    --with-R=pathToScript    Fully qualified path to R main script

You may need to specify "--with-R" if the main R script is not in your
PATH or is somewhere other than a reasonable default of "/usr/local/bin/R".

Note that R has a number of executable scripts and binaries but only
the primary one will suffice in this case.


USING IT
========

Fire up your tclsh:

    tclsh8.6
    % package require Rtcl
    1.1

Use `man Rtcl` for further details.

If you are running FreeBSD you may see the following error when you
try to load the library directly or require the Rtcl package:

    couldn't load file "/usr/local/lib/Rtcl1.1/libRtcl1.1.so": /lib/libgcc_s.so.1:
    version GCC_4.6.0 required by /usr/local/lib/gcc6/libgfortran.so.3 not found

If this happens to you follow the instructions in "FreeBSD Notes" to
resolve the error.


KNOWN TO WORK ON
================

- FreeBSD 11.1 with Tcl 8.6.8 and R 3.4.4
  Reported by Matt Adams

- Ubuntu 14.4 LTS with Tcl 8.6.7 and R 3.4.4
  Reported by Luc Moulinier


FREEBSD NOTES
=============

Since R (either installed as a package or from ports) is compiled
using gcc6 vs. the system cc (another long story), care must be taken
to ensure that this extension is built with similar conditions. I use:

   $ make distclean
   $ autoconf
   $ CC=gcc6 ./configure --with-tcl=/usr/local/lib/tcl8.6
   $ make
   $ make test
   $ su
   # make install
   # exit
   $

However, on FreeBSD there is a long standing issue with libgcc_s.so in
base that affects loading of this extension.

Building this extension using gcc6 will cause it to be compiled and
linked against the newer gcc libs but at run time `tclsh` finds the
base lib first and loads that. Unfortunately, base libgcc_s doesn't
support loading this extension (if the gcc6 libgcc_s was always
installed and found first then we wouldn't have this problem).

To workaround this issue for the dynamic linker, you must start
`tclsh` with the correct LD_LIBRARY_PATH. I have found that it is best
to use the same value as R. This will ensure that the gcc6 libs are
found, since R depends on those itself.

Assuming R exists in your PATH, you can run the following command to
determine R_HOME and set LD_LIBRARY_PATH accordingly (assumes
/bin/sh):

    $ export R_HOME=`echo 'cat(R.home())' | R --slave`
    $ . $R_HOME/etc/ldpaths
    $ /path/to/tclsh your_script.tcl

You can also find R's LD_LIBRARY_PATH by running:

    $ export LD_LIBRARY_PATH=`echo 'cat(Sys.getenv("LD_LIBRARY_PATH"))' | R --slave`
    $ /path/to/tclsh your_script.tcl

If you are using a shell wrapper script to start your Tcl program as
mentioned in https://wiki.tcl.tk/812 then you may use the following
wrapper code:

    #!/bin/sh
    # -*- tcl -*-
    # Wrapper script for running Tcl with command line invocation
    # The next line is executed by /bin/sh, but not tcl \
        R_HOME=$(echo 'cat(R.home()' | R --slave); . $R_HOME/etc/ldpaths; exec tclsh8.6 "$0" ${1+"$@"}

    # Tcl code continues here
    puts "Hello, World"

Yes, it's ugly. I don't know a way around it besides messing with
/etc/libmap.conf or /usr/local/etc/libmap.d and you may not want to do
that if other things run on your system and happen to depend on base
libgcc_s lib.

I am currently building this extension using gcc6 6.4.0 on FreeBSD
11.1-RELEASE-p9 with Tcl 8.6.8 (TEA 3.13) and R 3.4.4. All related
software is installed from packages. YMMV if you use ports or have
changed default configurations.


HISTORY
=======

Versions 0.1 through 0.3 were initially developed and released by Neil
McKay on Redhat Linux 8. Versions 1.0 and later were revised and
packaged by Matt Adams on FreeBSD 11.

See ChangeLog for detailed notes.


VERSION NUMBERS
===============

New releases require version number changes in the following files:

README
configure.ac (line 22)
doc/Rtcl.tmml
doc/Rtcl.n
tests/rtcl.test (line 27)