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From: [e-mail] (Joe Moss)
Subject: FAQ: comp.lang.tcl Tcl Language Usage Questions And Answers
Message-ID: <tcl-faq/[e-mail]>
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Summary: Answers to common questions regarding the use of the
    Tcl language and building the Tcl interpreter
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                   TCL LANGUAGE USAGE QUESTIONS AND ANSWERS

INTRODUCTION

   This FAQ file is intended to address some of the most commonly asked
   questions regarding the Tcl programming language. It is hoped that by
   addressing these here in this document, that the postings to
   comp.lang.tcl will be of a less repetitive and more informative
   nature. It is also hoped that via this and other available resources,
   more and more people will be able to utilize Tcl and Tcl based
   applications.

   This FAQ is posted monthly to comp.lang.tcl and news.answers and can
   also be obtained from the Tcl archive at ftp.aud.alcatel.com
   (198.64.191.10) in the /tcl/docs directory or via the World Wide Web
   as http://route.psg.com/tcl.html.

   For further information regarding Tcl see the FAQ maintained by Larry
   Virden ([e-mail]). It contains pointers to other available
   documentation and to many extensions and sample code. It too is
   available from alcatel in the /tcl/docs directory (as the files
   tcl-faq.part0[1-5].gz) or via the URL:
   http://www.cis.ohio-state.edu/hypertext/faq/usenet/tcl-faq/top.html

   Note that this FAQ deals with Tcl, not with Tk. For Tk Toolkit Q&As
   see the posting by Thomas J. Accardo ([e-mail]). However, there is
   some inevitable overlap. Some of the most commonly asked questions
   about usage of the Tk widgets are due to mis-understandings of how the
   Tcl interpreter works. These issues may still be addressed here. Also,
   some examples of Tcl usage may involve the use of the Tk widgets.

   Questions and Answers about the use of non-Tk related extensions (such
   as Extended Tcl and Expect, but not TkX, expectk, BLT, etc.) are also
   appropriate here.

   The source of this document is now maintained in HTML. It is then run
   through a couple of scripts (written in Tcl, of course) to
   automagically add question numbers, generate the Index of Questions,
   and add the From and Subject lines to the text version. The version
   available via the WWW will be updated whenever there are changes,
   while the ASCII text version will be generated and posted only once a
   month.
     _________________________________________________________________

Index of Questions:

     * Q1- Where I can find help getting Tcl to work on my machine?
     * Q2- How can I create/use association lists or property lists?
     * Q3- How can I generate a random number in Tcl?
     * Q4- How can I call one proc with the multi parameter value
       returned by another proc?
     * Q5- How can I pass an array into a proc?
     * Q6- How can I run an external command and read its output via a
       pipe?
     * Q7- How can I merge extended Tcl with wish, expect, etc.?
     * Q8- How can I delete a procedure from within a script?
     * Q9- How can I get parray to recognize an array created via upvar?
     * Q10- How can I get more than 7 digits of double precision ?
     * Q11- How can I grab the command line when a non-built-in call is
       made?
     * Q12- How can I get or set an environment variable?
     * Q13- How can I use numbers with leading zeroes?
     * Q14- How can I find the command line arguments to my application?
     * Q15- How can I put comments in my script, e.g. in a case
       statement?
     * Q16- How can I input and output binary data?
     * Q17- How can I trap signals, and other more Unix specific
       functions?
     * Q18- How can I get quoted strings to work the way I want?
     * Q19- How can I share procedures between multiple tcl applications?
     * Q20- How can I get items inserted into a list?
     * Q21- How can I perform a non-blocking read on a file identifier?
     * Q22- How can I read and write from a pipe without locking up?
     * Q23- How can I find what version I am running?
     * Q24- How do I create a stand alone program in case Tcl isn't
       installed?
     * Q25- How can I use variables to hold array names?
     * Q26- How can I create shared Tcl/Tk libraries on AIX
     * Q27- Has anyone gotten Tcl to compile under HP-UX?
     * Q28- Has anyone gotten Tcl to compile under VMS?
     * Q29- What does it take to get Tcl to compile under SCO Unix?
     * Q30- Why do I get format and scan errors when I run tclTest?
     * Q31- Why do I get lots of errors under Irix 4.0.1 when I run
       tclTest?
     * Q32- Does anyone else have problems with Tcl on a Cray?
     * Q33- How do I install Tcl 7.1/Tk 3.4 on NeXTSTEP 3.1?
     * Q34- Why can't I print the draft of the Tcl/Tk book?
     * Q35- Why am I getting errors on my SGI Indigo workstation?
     * Q36- How do I build expect on Solaris 2.3?
     * Q37- How do I port Tcl and Tk to a Sequent?
     * Q38- How do I get around the symbol table full msg in AU/X 3.0?
     * Q39- How do I compile Tcl on MS-DOS, MacOS, or other non-UNIX
       system?
     * Q40- How do I get Tcl to compile on my QNX system?

     _________________________________________________________________

------------------

From: TCL Q&A
Subject: Q1- WHERE I CAN FIND HELP GETTING TCL TO WORK ON MY MACHINE?

   Look in the Tcl distribution for the file called porting.notes. This
   will contain a collection of notes that various people have provided
   about porting Tcl to various machines and operating systems. There is
   also a file called README which should be read FIRST - before doing
   anything else with the code (this should always be one's first step
   with any package).

   There are also several questions and answers related to building the
   interpreter on various platforms at the end of this document.

------------------

From: TCL Q&A
Subject: Q2- HOW CAN I CREATE/USE ASSOCIATION LISTS OR PROPERTY LISTS?

   Use Extended Tcl arrays or keyed lists.

   For example, if you did a:

    keylset ttyFields ttyName tty1a
    keylset ttyFields baudRate 57600
    keylset ttyFields parity strip

   And then an echo $ttyFields, you'd get:

    {ttyName tty1a} {baudRate 57600} {parity strip}

------------------

From: TCL Q&A
Subject: Q3- HOW CAN I GENERATE A RANDOM NUMBER IN TCL?

   Extended Tcl includes a command named random to do this. For example,
   to generate a random number between 0 and 9 inclusive:

    set random_number [random 10]

   It also has a srandom command to seed the random number generator.

   Several pseudo-random number generator functions, written in straight
   Tcl, have been posted to comp.lang.tcl and are available from alcatel.

   To get a value you can use as a seed, you might try one (or a
   combination) of these:

        [pid]
        [file atime /dev/kmem]
        [getclock]              (Extended Tcl only)

------------------

From: TCL Q&A
Subject: Q4- HOW CAN I CALL ONE PROC WITH THE MULTI PARAMETER VALUE RETURNED
  BY ANOTHER PROC?

   Assuming y requires multiple args and x returns multiple words, use
   Tcl's eval command :

    eval y [x]

------------------

From: TCL Q&A
Subject: Q5- HOW CAN I PASS AN ARRAY INTO A PROC?

   Use upvar rather than try to use global variables when possible. If
   the function is event driven, you are forced to use global variables.

    # print elements of an array
    proc show_array arrayName {
        upvar $arrayName myArray

        foreach element [array names myArray] {
           puts stdout "${arrayName}($element) =  $myArray($element)"
        }
    }

    set arval(0) zero
    set arval(1) one
    show_array arval

   To return an array from a procedures, just take the array name in as
   an argument, as above. Any changes you make in the array will be made
   in the parent's array as well.

   Extended Tcl introduces a concept called keyed lists which are arrays
   made out of lists of key-value pairs and can be passed by value to
   routines, over networks, etc.

------------------

From: TCL Q&A
Subject: Q6- HOW CAN I RUN AN EXTERNAL COMMAND AND READ ITS OUTPUT VIA A
  PIPE?

   For example, to grep a pattern out of a range of files, one might do:

   Karl Lehenbauer ([e-mail]) writes:

    set files [glob /home/cole/stats/*]

    proc parseInfo { site } {
       global files

    #
    # site is chosen from a listbox earlier
    #
       set in [open [concat "|/usr/bin/grep $site $files"] r]

       while {[gets $in line]>-1} {
          puts stderr $line
       }
       catch {close $in}
    }

   One thing: the matching strings are _not_ returned in directory order.

   But what if I want to check the return code AND use the output of the
   command? Kevin B. Kenny ([e-mail]) writes:

    if [catch {exec ls} data] {
        # The exec got an error, and $errorCode has its termination status
    } else {
        # The exec succeeded
    }
    # In any case, `data' contains all the output from the child process.

   Note that Karl Lehenbauer ([e-mail]) adds that errorCode will
   be a list containing three elements, the string "CHILDSTATUS", the
   process ID of the child, and the exit status of the child.

------------------

From: TCL Q&A
Subject: Q7- HOW CAN I MERGE EXTENDED TCL WITH WISH, EXPECT, ETC.?

   Extended Tcl, as of version 6.7c, was enhanced to make it easier to
   incorporate into applications.

------------------

From: TCL Q&A
Subject: Q8- HOW CAN I DELETE A PROCEDURE FROM WITHIN A SCRIPT?

   Rename the procedure to have no name, for example:

    rename procedureName ""

------------------

From: TCL Q&A
Subject: Q9- HOW CAN I GET PARRAY TO RECOGNIZE AN ARRAY CREATED VIA UPVAR?

   Right now (June, 1992) upvar doesn't allow you to attach to an
   individual element of an array. This is considered a bug by Mr.
   Ousterhout and has been place on a bug list.

------------------

From: TCL Q&A
Subject: Q10- HOW CAN I GET MORE THAN 7 DIGITS OF DOUBLE PRECISION ?

   In Tcl 6.x, modify the tclExpr.c module to use %lf instead of %g. In
   Tcl 7.x, set the global variable tcl_precision instead.

------------------

From: TCL Q&A
Subject: Q11- HOW CAN I GRAB THE COMMAND LINE WHEN A NON-BUILT-IN CALL IS
  MADE?

   The procedure unknown is called automatically with arguments
   containing the command and its arguments for any command that couldn't
   be found. In fact, Tcl and Extended Tcl use this feature to provide
   demand loaded commands, and even entire libraries.

   So by modifying the unknown procedure you can provide your own
   extended functionality, or even remove the demand loading capability
   if you so desire.

------------------

From: TCL Q&A
Subject: Q12- HOW CAN I GET OR SET AN ENVIRONMENT VARIABLE?

   By using something like the following.

    set olddisplay $env(DISPLAY)
    set env(DISPLAY) unix:0

   Thanks to Joel Fine ([e-mail]) for the answer.

   You can also check if an environment variable exists, like this:

    if [info exists $env(VARNAME)] {
            # okay, it's there use it
            set value $end(VARNAME)
    } else {
            # the environment var isn't set, use a default
            set value "the default value"
    }

------------------

From: TCL Q&A
Subject: Q13- HOW CAN I USE NUMBERS WITH LEADING ZEROES?

   Dave Morriss was recently having problems because he was trying to do
   something like:

    set index [expr [exec date +%W]%[llength $pop_server_list]]

   but during the 8th and 9th week of the year, he got errors - 08 and 09
   are not valid octal numbers in Tcl.

   Some of the solutions provided were:

   From George A. Howlett ([e-mail]), we got:

    set wknum [format "%g" [exec date +%W]]
    set index [expr [exec $wknum%[llength $pop_server_list]]

   From Fred Feirtag ([e-mail]):

    set index [expr (1[exec date +%W]-100)%[llength $pop_server_list]]

   From Dan R. Schenck ([e-mail]):

    set index [expr [string trimleft [exec date +%W] 0]%[llength \
                     $pop_server_list]]

   Jay Goldberg [e-mail] points out that while all of the
   above work in this case (dealing with a date) they don't work in the
   general case.

   Instead you can use the statement:

    regsub 0+(.+) orig_string \\1 new_string

   to strip off leading zeros. So, applying this to the example above:

    regsub 0+(.+) [exec date +%W] \\1 weeknum
    set index [expr $weeknum%[llength $pop_server_list]]

------------------

From: TCL Q&A
Subject: Q14- HOW CAN I FIND THE COMMAND LINE ARGUMENTS TO MY APPLICATION?

   If you are using extended Tcl or Expect, you will find the parameters
   in the Tcl variable argv as a list. Note that in extended Tcl, the
   name of the program is in the Tcl variable programName and NOT in
   argv[0]. Thanks to Brad Morrison ([e-mail]) and Bud Bach
   ([e-mail]) for this answer.

------------------

From: TCL Q&A
Subject: Q15- HOW CAN I PUT COMMENTS IN MY SCRIPT, E.G. IN A CASE STATEMENT?

   You can't have comments where you have them. Move the comments inside
   of the { for the case that you want. Your code should read:

    case 1 {
      -1    {
            #
            # Cannot find information sought
            #
            exit 2
            }
       0    {
            #
            # Error in arguments
            #
            exit 1
            }
       default    {
            #
            # Desired information found
            #
            exit 0
            }
    }

   Thanks to Gerald W. Lester ([e-mail]).

------------------

From: TCL Q&A
Subject: Q16- HOW CAN I INPUT AND OUTPUT BINARY DATA?

   With Extended Tcl you can safely do stuff like:

    set infp [open "|compress -dc $fileName"]
    set outfp [open "|gzip -c $newFileName" w]

    copyfile $infp $outfp

   Thanks to Karl Lehenbauer ([e-mail]) for the code example.

   A method of handling binary data one character at a time using
   standard Tcl can be found in:
   ftp.aud.alcatel.com:/tcl/code/binary-io-hack.shar.gz

------------------

From: TCL Q&A
Subject: Q17- HOW CAN I TRAP SIGNALS, AND OTHER MORE UNIX SPECIFIC
  FUNCTIONS?

   Extended Tcl offers many of these types of functions. For instance,
   extended Tcl has the signal command:

     signal action siglist [command]

     where action is one of "default", "ignore", "error", "trap", "get",
     plus the POSIX "block" and "unblock" actions (available only on
     POSIX systems, of course). Siglist is a list of either the symbolic
     or numeric Unix signal (the SIG prefix is optional). Command is your
     error handler (or a simple {puts stdout "Don't press *that* key!"}
     :-)

   trap does what you expect, and I find error and get to be extremely
   useful in interactive programs which demand keyboard traversal.

   Extended Tcl also has things like fork, etc.

   Answer by Brad Morrison ([e-mail]).

------------------

From: TCL Q&A
Subject: Q18- HOW CAN I GET QUOTED STRINGS TO WORK THE WAY I WANT?

   A long article dealing with the issues can be found at
   ftp://ftp.aud.alcatel.com/tcl/docs/README.programmer.gz

   Here are some short answers:

   Q. I'm trying to build up a command for later execution but am having
   trouble with variable values that include whitespace or special
   characters.

   A. The safest way to build up commands is to use the list command so
   that you can keep track of the list structure. Avoid using double
   quotes because you can end up with an extra trip through the
   evaluator. We'll illustrate this with a command to create a button
   that prints out the label on the button when you click it.

     Wrong answer #1:

    button $myname -text $label -command "puts stdout $label"

     Why? because if $label has whitespace then the puts command will be
     passed the wrong number of arguments. If $label has $ or [ ]
     characters, they will be interpreted instead of printed.
     Good answer #2:

    button $myname -text $label -command [list puts stdout $label]

     Why? because list will properly quote the value of $label

   Q. I'm trying to build up a command for later execution but am having
   trouble getting some variables to evaluate now, and some to evaluate
   later when the command is run.

   A. The cleanest way to do this is to define a procedure that hides the
   use of the variables at run time, and then build up a call to that
   procedure using the list command as described previously. (You can
   even define the procedure on the fly. It will have global scope even
   it if is created within another procedure.)

     Wrong answer #1:

    button $myname -text $label -command \
        [list puts stdout $ArrayOfDynamicStuff($label)]

     Why? The array value will be substituted when the button is created,
     not later on when the button is clicked. Also, note that the command
     is executed at the global scope, so it is not necessary to include a
     "global ArrayOfDynamicStuff" in the command.
     Wrong answer #2 (backquotes and list):

    button $myname -text $label -command \
        [list puts stdout \$ArrayOfDynamicStuff($label)]

     Why? Here the list command and the backquote of $ are fighting with
     each other. The command ends up being something like:

    puts stdout {$ArrayOfDynamicStuff(foo)}

     which prevents the substitution of the value of the array element.
     Dubious answer #3 (backquotes and double-quotes):

    button $myname -text $label -command \
        "puts stdout \$ArrayOfDynamicStuff($label)"

     Why? This only works if the value of $label has no special
     characters or whitespace.
     Clean answer #4 (proc):

    proc doit { i } {
        global ArrayOfDynamicStuff
        puts stdout $ArrayOfDynamicStuff($i)
    }
    button $myname -text $label -command [list doit $label]

     Why? Using little TCL procs for your button commands is a good habit
     because it eliminates most needs for fancy quoting, and it makes it
     easier to tweak the button command later on.

   Q. I'm trying to pass along a variable number of args to another
   procedure but I'm having trouble getting the $args to expand right.

   A. Avoid using eval and double quotes because that results in an extra
   trip through the interpreter. The eval command will do a concat of its
   arguments if there are more than one, so that pretty much eliminates
   the need to group things with double quotes. Let's extend the button
   example:

     Wrong answer #1:

    proc mybutton { myname label args } {
        button $myname -text $label -command [list puts stdout $label] $args
    }

     Why? All the extra arguments to mybutton are grouped into one list
     element that is but into the value of $args. However, the button
     command expects to see individual arguments, not a sub-list.
     Wrong answer #2:

    proc mybutton { myname label args } {
        eval "button $myname -text $label -command [list puts stdout $label] $a
rgs"
    }

     Why? The double quotes allow expansion of $label as well as $args,
     so if $label has any whitespace, the button command will be
     malformed
     Good answer #3:

    proc mybutton { myname label args } {
        set cmd {button $myname -text $label -command [list puts stdout $label]
}
        eval $cmd $args
    }

     Why? Eval will first concatenate its two arguments and then run the
     result through the interpreter. Think of this as stripping off the
     outer curly braces from $cmd and $arg and making a single list with
     all the elements of both. $label will be evaluated exactly once, so
     the puts command will remain good, and whatever went into args will
     also be processed exactly one time.

   Q. Why do I get a syntax error in an if/while/for statement?

   A. You may have written something like

    wish: set foo bar
    wish: if {$foo == bar} {puts stdout bar}
    syntax error in expression "$foo == bar"

   in which bar is interpreted as neither a string nor a variable, since
   strings as operands in expressions MUST be surrounded by double quotes
   or braces.

   Change to

    wish: if {$foo == "bar"} {puts stdout bar}

   or

    wish: if {$foo == {bar}} {puts stdout bar}

   always in expressions, depending on if you want expansion performed or
   not.

   Contributed by Jesper Blommaskog ([e-mail]).

------------------

From: TCL Q&A
Subject: Q19- HOW CAN I SHARE PROCEDURES BETWEEN MULTIPLE TCL APPLICATIONS?

   Rather than sourcing the files explicitly, build a tcl library:

   Step 1. Put the files in a common directory

   Step 2. Build the tclIndex for the "library". I use a Makefile with a
   convention like:

    install.index:
        (cd ${DESTDIR}/tclscripts/lib; \
        echo 'source /usr/local/lib/tcl/init.tcl;\
        auto_mkindex . *.tk' | tcl ; exit 0)

   Step 3. Modify your tcl scripts to reference the library:

   e.g.:

    # local additions
    lappend auto_path /usr/local/lib/tcl_local $env(RDS_TCL_SCRIPTS)/lib

   Now, as soon as your script tried to reference a procedure in the
   library, the "unknown" command autoloads the procedure for you.

   Contributed by Joe VanAndel ([e-mail]).

------------------

From: TCL Q&A
Subject: Q20- HOW CAN I GET ITEMS INSERTED INTO A LIST?

   A user asked why

    linsert $list 0 ..

   did not result in .. being inserted into list.

   Jesper Blommaskog ([e-mail]) replied:

   When doing list operations other than lappend, you must save the
   returned value. This applies to list, lindex, lrange, and lreplace at
   least.

   In this example, you would perhaps want to do something like:

    set list [ linsert $list 0 .. ]

------------------

From: TCL Q&A
Subject: Q21- HOW CAN I PERFORM A NON-BLOCKING READ ON A FILE IDENTIFIER?

   From Frank Smith ([e-mail]) we are told that if
   you have Extended Tcl, you can

    read $fileId [fstat $fileId size]

   This will read only the number of bytes currently available on fileId
   and consequently will not block.

------------------

From: TCL Q&A
Subject: Q22- HOW CAN I READ AND WRITE FROM A PIPE WITHOUT LOCKING UP?

   The stdio package has an optimization for speed that buffers
   characters so that you can avoid un-necessary system calls. This isn't
   very good for interactive use so stdio changes it's behaviour if the
   file is a terminal. When you write to a pipe you are not writing to a
   terminal and so your output is buffered, similarly when the program at
   the other end of the pipe writes its response it is also buffered. The
   end result is the programs at both end of the pipe stall waiting for
   input. It is possible to force the buffers to be written using flush
   in Tcl and fflush() in C, often though, you don't have control over
   the program at the other end of the pipeline and in that case your
   only solution is to use a pseudo-teletype (pty). Unfortunately this
   isn't all that easy.

   While this isn't directly supported in Tcl the spawn command in expect
   opens a pty and starts a command.

------------------

From: TCL Q&A
Subject: Q23- HOW CAN I FIND WHAT VERSION I AM RUNNING?

   Well, there is no one answer to this. Tcl itself will tell you it's
   version if you type:

    info tclversion

   On the other hand, to get the Tk version, you must use:

    puts $tk_version

   Other extensions use other means.

------------------

From: TCL Q&A
Subject: Q24- HOW DO I CREATE A STAND ALONE PROGRAM IN CASE TCL ISN'T
  INSTALLED?

   Earle Lowe ([e-mail]) has replied that:

     If you want to create a stand-alone program that will run anywhere
     regardless of the presence/absence of TCL/Tk, than you need to go
     through some more work. Basically, this involves converting the TCL
     init files to C strings, and then rather than calling Tcl_Init() and
     Tk_Init(), you call Tcl_Eval() with the converted C strings as
     arguments. I suggest getting the wish_compiler package by Alexei
     Rodriguez ([e-mail]) from
     ftp://ftp.aud.alcatel.com/tcl/code/wish_compiler.shar.gz This
     package contains a tcl2c converter, and instructions as to its use.
     With some Makefile magic, you can use using TCL/Tk as intended (as
     an interpreted language using some version of wish) and when the
     code works, you can create a stand-alone compiled program.

------------------

From: TCL Q&A
Subject: Q25- HOW CAN I USE VARIABLES TO HOLD ARRAY NAMES?

   Eric Bleeker ([e-mail]) has written:

     You may have written something like:

    % set foo "bar baz"
    bar baz
    % foreach aap $foo {
        set $aap(1) "something"
    }
    can't read "aap(1)": variable isn't array

     This means Tcl tries to substitute the array element aap(1) which
     doesn't exist. To fix this use:

    % foreach aap $foo {
        set [set aap](1) "something"
    }

     In this case two arrays bar and baz are created.

------------------

From: TCL Q&A
Subject: Q26- HOW CAN I CREATE SHARED TCL/TK LIBRARIES ON AIX

   Dov Grobgeld ([e-mail]) provided info on creating Tcl
   and Tk shared libraries under AIX 3.1.5:

     For Tcl:

    cc -o tkshar.o *.o -bE:tclshar.exp -bM:SRE -berok -lX11 -lm
    ar r libtclshr tclshar.o

     For Tk:

    cc -o tkshar.o *.o -bE:tkshar.exp -bM:SRE -berok -Ltcl -lX11 -lm -ltclshr
    ar r libtkshr tkshar.o

     where tckshar.exp and tkshar.exp had lists of the external
     functions.

     There are also problems with fonts on AIX and the IBM. A patch is
     needed from IBM to fix the X server so that fonts are working

------------------

From: TCL Q&A
Subject: Q27- HAS ANYONE GOTTEN TCL TO COMPILE UNDER HP-UX?

   See the porting notes. Also, be aware that there have been some
   reports of Configure assuming that you should use the compatibility
   version of opendir() and that you have no dirent.h . This causes
   glob-ing to fail, as well as TclX's readdir, etc.

   Changing tcl7.3 to remove the opendir compatibility file and removing
   the -DNO_DIRENT, -DUSE_DIRENT2 fixed it all up.

------------------

From: TCL Q&A
Subject: Q28- HAS ANYONE GOTTEN TCL TO COMPILE UNDER VMS?

   Information from John Kimball ([e-mail]) on May 4,
   1993 was that he had gotten Tcl 6.7 and Tk 3.2 ported to VMS 5.5. See
   the catalog for the file information.

------------------

From: TCL Q&A
Subject: Q29- WHAT DOES IT TAKE TO GET TCL TO COMPILE UNDER SCO UNIX?

   Add a "#undef select" to tkEvent.c, and remove the reference to
   TK_EXCEPTION around line 460 of main.c.

   Tk uses its own scheme for allocating the border colors for its 3D
   widgets, which causes problems when running TK on a system with
   "PseudoColor" display class, and a 16-cell colormap.

   If you can't go to eight bitplanes, you can instead start the server
   with a "-static" (Xsco) or "-analog" (Xsight) option, making the
   display class become "StaticColor". This makes the entire colormap
   read-only, and it will return the color that most closely maps to the
   desired color as possible.

   This information is from Keith Amann ([e-mail]).

------------------

From: TCL Q&A
Subject: Q30- WHY DO I GET FORMAT AND SCAN ERRORS WHEN I RUN TCLTEST?

   That's a problem (scanf/printf) many systems seem to have. Don't worry
   too much about it - just don't use these 'advanced' features. If
   you're hacking C, you'll have the same problems.

   For instance, printf("%Ng, double_value) and strtod("+",&terminal)
   produce incorrect results.

------------------

From: TCL Q&A
Subject: Q31- WHY DO I GET LOTS OF ERRORS UNDER IRIX 4.0.1 WHEN I RUN
  TCLTEST?

   There's a bug in the 4.0.1 optimizer that's fixed in 4.0.2. Compile
   tclVar.c using -O0 (no optimization).

------------------

From: TCL Q&A
Subject: Q32- DOES ANYONE ELSE HAVE PROBLEMS WITH TCL ON A CRAY?

   See the porting notes for a set of changes mentioned. Also, Booker C.
   Bense ([e-mail]) reports that version 3.0.1.6 has some
   real problems with char pointers, causing Tcl to crash. Using version
   3.0.2.1, things are much better, except for a minor formatting problem
   and serious problems with scan.

------------------

From: TCL Q&A
Subject: Q33- HOW DO I INSTALL TCL 7.1/TK 3.4 ON NEXTSTEP 3.1?

   I have indicated in the past that this particular question seems to
   generate controversy - I have replaced previous explanations with the
   latest msg from someone who sounds authoritative...

   From: Robert Nicholson ([e-mail])

     This is for TCL7.1 and TK3.4

     This is a variation on Thomas Funke's entry.

    Installing TCL7.1 on NeXT

     To install tcl7.1 on NeXTSTEP 3.1 you must:
     * run configure with predefined CPP:
       type "sh" to run a Bourne shell. then type

    CPP='cc -E' ./configure
     * edit Makefile:
       add tmpnam.o to COMPAT_OBJS:

  COMPAT_OBJS =      getcwd.o waitpid.o strtod.o tmpnam.o

     At this point you probably want to rename the all calls to strtod
     and tmpnam to something else in order to distinguish them from those
     that are supplied in the NeXT libraries libsys_a.a. You can do this
     by adding the following line to AC_FLAGS

    -Dstrtod=newstrtod -Dtmpnam=newtmpnam

     and renaming the names of the definitions in the appropriate
     compat/*.c files.

     To check everything is working correctly open a tclsh

    % expr {"0" == "+"}
    0

     Using the wrong strtod function will cause this test to return 1
     which is a serious error. Ignore the precision errors.

    Installing TK3.4 on NEXTSTEP 3.1

     There is a call to strtod in TK3.4 so you should link against
     ../tcl-7.1/compat/strtod.o and apply the -Dstrtod=newstrtod to
     AC_FLAGS in Tk also.

     Note:Tk's raise test will fail when running the tvtwm window
     manager. Changing to either twm or even better fvwm ensures that
     this test will succeed.

------------------

From: TCL Q&A
Subject: Q34- WHY CAN'T I PRINT THE DRAFT OF THE TCL/TK BOOK?

   From John Ousterhout ([e-mail]):

   Here's my form letter that seems to explain most of the problems
   people have had printing parts of the book:

   Some old versions of the Transcript spooler software cannot properly
   handle encapsulated Postscript files within another Postscript file
   when they do page reversal. They tend to garble the page structure of
   the file, causing an error at the point of the first EPS file. Part II
   of the Tcl book has lots of EPS files embedded in it, one for each
   screen dump. If your printer cannot print this file I suggest checking
   to see if page reversal is enabled for your printer. If so, try asking
   your local system wizard to disable it for you; this should allow the
   file to print. Or, find some other way to dump the Postscript file
   directly to the printer without going through the spooling software
   (e.g. perhaps you can simply cat it to the printer's serial port).

   Others have suggested:

   The embedded pictures have CR as the line separator instead of LF and
   this may be causing the problem. Try translating them to LFs ...

    tr '\015' '\012' <book.p2.ps >fixedbook.p2.ps

   and:

   This is not the original poster's problem but in countries using A4
   paper and on a particular printer, the Dataproducts LZR1260E, the
   frame size causes the printing to be stretched vertically. This
   happens with other Framemaker generated documents by the way. A PS
   interpreter bug no doubt. The fix is to edit the dimensions for A4
   paper. This shell script does both fixes.

    #!/bin/sh
    cat $1 | tr '\015' '\012' | sed '/FMDOCUMENT$/s/612 792/595 842/'

------------------

From: TCL Q&A
Subject: Q35- WHY AM I GETTING ERRORS ON MY SGI INDIGO WORKSTATION?

   From Gordon Lack ([e-mail]) we are told that the SGI c
   compiler has some bugs with variable arguments.

   tclVar.c must be compiled with -O0 at IRIX C 4.0.1 because of a
   compiler bug with varargs.

   Done by placing specific rule into Makefile.

    # GGR SG needs -O0 for varargs at 4.0.1

    CC_SWITCHES0 =  -O0 -I. -I${SRC_DIR} ${AC_FLAGS} ${MATH_FLAGS} \
          ${GENERIC_FLAGS} ${PROTO_FLAGS} ${MEM_DEBUG_FLAGS} \
          -DTCL_LIBRARY=\"${TCL_LIBRARY}\"

    tclVar.o: tclVar.c
          $(CC) -c $(CC_SWITCHES0) $

Peter Neelin ([e-mail]) also noted that:

I get tclX 7.3a to compile on an SGI (irix 4.0.5) with the following
changes to the Config.mk file:

    71c71
    < CFLAGS=-cckr -D__GNU_LIBRARY__
    ---
    > #CFLAGS=
    106,107c106,107
    < TCL_PLUS_BUILD=TCL_PLUS
    < CCPLUS=g++
    ---
    > #TCL_PLUS_BUILD=TCL_PLUS
    > CCPLUS=CC
    191,193c191
    < MAN_DIR_SEPARATOR=
    <
    < LIBOBJS=strftime.o
    ---
    > #MAN_DIR_SEPARATOR=.

The -D__GNU_LIBRARY solves the srandom problem and I think that the -cckr gets
around the prototype error with waitpid (it's crude, but it works).
I've forgotten why I needed the strftime.

If you want the version of Config.mk that worked for me, send me mail.

------------------

From: TCL Q&A
Subject: Q36- HOW DO I BUILD EXPECT ON SOLARIS 2.3?

From Jeff Abramson ([e-mail]) we are told that,

     using either SunPro cc 2.0.1 or gcc 2.5.8 with no problems. For
     SunPro I do:

    CC=cc ./configure --prefix=directory_of_your_choice
    make CC=cc

     For gcc I do:

    CC="gcc -fwritable-strings" ./configure \
        --prefix=directory_of_your_choice
    make CC="gcc -fwritable-strings"

------------------

From: TCL Q&A
Subject: Q37- HOW DO I PORT TCL AND TK TO A SEQUENT?

From Andrew Swan ([e-mail]) we find:

     For both Tcl and Tk, I used gcc rather than the Sequent cc which is
     not ansi.

     For Tcl, there were a couple of problems with the math library.
     First, the Sequent math library doesn't include the 'fmod' function.
     I got the source for fmod from ftp.uu.net, put it in the compat
     subdirectory, and added it to the Makefile. fmod also wanted
     functions 'isnan' and 'finite' but I just commented those out since
     I don't believe tcl supports infinity and nan.

     The other problem with the math library was that it has two copies
     of the 'tanh' function in it. This is easy to fix by using "ar" to
     separate the library in to object files and then reconstruct it,
     leaving one of the copies of tanh out.

     With those changes, Tcl compiled cleanly and passed all the tests
     except the scanning tests. Apparently, the *scanf functions are
     broken in Dynix. The problem is with recognizing the end of octal
     numbers, and I just let this problem go. Fixing it would probably
     involve finding source to the *scanf functions and including it.

     To compile Tk, I had to make a new version of stddef.h including
     things like wchar_t. I just copied it in to another include
     directory and put that directory first and then tweaked the copy. Tk
     also had the math library problem (tanh). Other than those, however,
     everything compiled cleanly and passed all the tests.

------------------

From: TCL Q&A
Subject: Q38- HOW DO I GET AROUND THE SYMBOL TABLE FULL MSG IN AU/X 3.0?

After getting things compiled on AU/X, you have to be sure
to do the links with the -A {factor} arguments which expand the default
table allocations.  {factor} is the amount by which the compiler multiplies
the default allocation.  Try -A 2.  Contact
Walter B. Kulecz, PhD. ([e-mail]) for more details
of his port.

------------------

From: TCL Q&A
Subject: Q39- HOW DO I COMPILE TCL ON MS-DOS, MACOS, OR OTHER NON-UNIX
  SYSTEM?

Refer to Larry Virden's FAQ (see tcl-faq/part1) or
(see tcl-faq/part4) for details concerning tools, finished
ports, or mailing lists relating to this topic.

------------------

From: TCL Q&A
Subject: Q40- HOW DO I GET TCL TO COMPILE ON MY QNX SYSTEM?

Steve Furr ([e-mail]) indicates:

For the record, to get TCL to work under QNX, I had to:

     * Make the _POSIX_SOURCE change indicated for pathname lengths
     * Change a definition of VARARGS, so the Watcom ANSI C compiler
       would accept varargs functions used.
     * Resolve a conflict with error codes defined by QNX.

  __________________________________________________________________________

End of FAQ

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