TweetFollow Us on Twitter

Tk: A Portable GUI Toolkit

Volume Number: 19 (2003)
Issue Number: 4
Column Tag: Section 7

Tk: A Portable GUI Toolkit

Expressiveness and Simplicity Count for a lot

by Rich Morin

Last month, I mentioned Tk, referring to it as an X11 toolkit. This month, I'd like to cover Tk in a bit more detail. I should begin, however, by clarifying that Tk is not just an X11 toolkit; in fact, it is a platform- and language-independent GUI toolkit.

Tk can be used with C, Perl, Python, Ruby, Tcl (Tk's original counterpart), and many other programming languages. It can be used with Aqua, PalmOS, X11, and assorted Microsoft APIs. In summary, any modern computer with the appropriate hardware probably has Tk support.

Tk also wins big on expressiveness and simplicity. Most GUI toolkits (e.g., Cocoa and assorted X11 "widget sets") are complex and have steep learning curves. Tk, in contrast, is remarkably simple to program, once a few basic concepts have been mastered. Although Tk may not have all the features of Cocoa, it supports most of the widgets you are likely to need; it also has ways to add new widgets, if you're feeling sufficiently motivated.


Because Tk started as a toolkit for the Tcl language, most of the Tk resources you'll find are actually for Tcl/Tk, the language/toolkit combination. Also, because Tcl/Tk is the focus of development, the other language bindings (e.g., Perl/Tk, Tkinter) occasionally lag behind. Finally, if you want to extend Tk, you'll probably find yourself coding some Tcl in the process.

In short, you should plan to learn a bit of Tcl, even if you intend to use Tk with some other language. Fortunately, this isn't particularly painful; Tcl syntax only takes about five minutes to learn (most of which you'll spend accepting the idea of how simple the syntax really is :-).

Pick up a copy of the Mac OS X Tcl/Tk port from:

Be sure to look at the ReadMe files; they contain a number of useful pointers and critical details. After the (dmg, mpkg) installation finishes, you should find a copy of "Wish Shell":


When you start up the app, two windows will appear. The "Console" window allows you to run Tcl commands, viewing the output:

set a 123
() 2 % set b [expr $a * 2]
() 3 %

Tcl isn't a conventional language and it isn't processed in a conventional manner. Although some parts of Tcl syntax look a bit like C or Perl, the interpreter is simply performing a sequence of commands and string substitutions. Thus, the first line sets a variable ("a") to the text string ("123"). You may think of this as a numeric value, but the Tcl interpreter doesn't.

The second line does three things. First, it performs a "variable substitution", replacing "$a" with the value "123". Next, it performs a "command substitution", replacing the expression "[expr $a * 2]" with the result (246). Finally, it sets "b" to the resulting value.

Now, let's bring Tk and the other (Wish Shell) window into play:

() 3 % button .b -text "Hello, world!" -command exit
() 4 % pack .b
() 5 %

If all went as expected, the "Wish Shell" window should now contain a button labeled "Hello, world!". Pushing that button should cause the Wish Shell to exit (and both of its windows to disappear). In two lines of code, you have created and run a (tiny) windowing application!

If you simply want to program in Tcl/Tk, you are now in a position to do so. The results will look nicely Aquafied (Aquatic?) and you don't have to tell anyone how little code you wrote! If you become intrigued with Tcl/Tk, be sure to pick up John Ousterhout's excellent (if dated) "Tcl and the Tk Toolkit" (Addison-Wesley). John created both Tcl and Tk, so he's eminently qualified to say how they should be used.


Although Tcl is syntactically interesting, extremely portable, and quite flexible, you may prefer (as I do) to do your actual programming in some other language. Perl/Tk allows Perl programmers to use Tk widgets, while keeping the rest of their code in Perl. As hinted above, analogous libraries are available for C, Python, Ruby, and other programming languages.

Having said this, I should note that Tk calls may not be a smooth fit into the syntax of the chosen language. Here is a Perl/Tk translation of our simple window example:

use Tk;
my ($b, $mw);
$mw = new MainWindow;
$b  = $mw->Button(-text    => 'Hello, world!',
                  -command => sub { exit; });

This code is substantially larger, but the original Tk commands and arguments are still present (albeit buried in Object-Oriented Perl syntax :-). Several lines of overhead code bring in the Tk module, declare a couple of variables, create a window, and finally, start up the Tk event loop. Also note that we are no longer using the Tcl exit command; instead, we have created an anonymous Perl function which uses Perl's own exit command.

If you want to play with Perl/Tk, your first step should be to purchase a copy of "Learning Perl/Tk" (Nancy Walsh, O'Reilly). Buy Ousterhout's book, too, if you can; you won't regret it!

Now for the bad news: installing Perl/Tk on Mac OS X is quite complex and (worse) still in a state of flux. It is possible, with some difficulty, to make Perl/Tk work with Apple's X11 server and Developer Kit. I don't know of a way to get Perl/Tk to work with the native Tk port (as installed above), but I hope to have more information by the time this column is in print. Look for instructions on

I also suggest, for the brave-hearted, the following links:

Rich Morin has been using computers since 1970, Unix since 1983, and Mac-based Unix since 1986 (when he helped Apple create A/UX 1.0). When he isn't writing this column, Rich runs Prime Time Freeware (, a publisher of books and CD-ROMs for the Free and Open Source software community. Feel free to write to Rich at


Community Search:
MacTech Search:

Software Updates via MacUpdate

ExpanDrive - Access cloud storag...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Markly 1.5.3 - Create measurement and de...
Markly is a measurement and design-spec plugin/extension for Photoshop and Sketch. It is made for modern Web designers and app front-end developers. You can add specification marks simply by clicking... Read more
Suitcase Fusion 6 17.3.0 - Font manageme...
Suitcase Fusion 6 is the creative professional's font manager. Every professional font manager should deliver the basics: spectacular previews, powerful search tools, and efficient font organization... Read more
Nisus Writer Pro 2.1.2 - Multilingual wo...
Nisus Writer Pro is a powerful multilingual word processor, similar to its entry level products, but brings new features such as table of contents, indexing, bookmarks, widow and orphan control,... Read more
calibre 2.40.0 - Complete e-book library...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more
Vivaldi - An advanced browser...
Vivaldi is a browser for our friends. In 1994, two programmers started working on a web browser. Our idea was to make a really fast browser, capable of running on limited hardware, keeping in mind... Read more
OmniPlan 3.0 - Robust project management...
With OmniPlan, you can create logical, manageable project plans with Gantt charts, schedules, summaries, milestones, and critical paths. Break down the tasks needed to make your project a success,... Read more
Yummy FTP 1.11 - FTP/SFTP/FTPS client fo...
Yummy FTP is an FTP + SFTP + FTPS file transfer client which focuses on speed, reliability and productivity. Whether you need to transfer a few files or a few thousand, schedule automatic backups, or... Read more
Tweetbot 2.1 - Popular Twitter client. (...
Tweetbot is a full-featured OS X Twitter client with a lot of personality. Whether it's the meticulously-crafted interface, sounds and animation, or features like multiple timelines and column views... Read more
MacPilot 8.0 - Enable over 1,200 hidden...
MacPilot gives you the power of UNIX and the simplicity of Macintosh, which means a phenomenal amount of untapped power in your hands! Use MacPilot to unlock over 1,200 features, and access them all... Read more

Balloony Land offers a fresh twist on th...
Balloony Land by Palringo offers a fresh twist on the match three genre and is out now on iOS and Android. First-off, you'll be popping balloons instead of crushing candy and the balloons will float up and fill the empty spaces instead of dropping... | Read more »
Graphic - vector illustration and design...
Graphic - vector illustration and design 1.0 Device: iOS iPhone Category: Productivity Price: $2.99, Version: 1.0 (iTunes) Description: Autodesk Graphic is a powerful full-featured vector drawing and illustration application right in... | Read more »
Sago Mini Babies (Education)
Sago Mini Babies 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: Introducing the Sago Mini babies. Boys and girls love caring for these adorable characters. Feed Robin her favorite mush... | Read more »
PAUSE - Relaxation at your fingertip (H...
PAUSE - Relaxation at your fingertip 1.1 Device: iOS iPhone Category: Healthcare & Fitness Price: $1.99, Version: 1.1 (iTunes) Description: | Read more »
Super Sharp (Games)
Super Sharp 1.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.1 (iTunes) Description: Your finger has never been so sharp! Cut with skill to complete the 120 ingenious physics levels of Super Sharp and become a cut... | Read more »
Assembly - Graphic design for everyone...
Assembly - Graphic design for everyone 1.0 Device: iOS Universal Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Assembly is the easiest most powerful design tool on the App Store. Create anything you can... | Read more »
Dub Dash (Games)
Dub Dash 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: ARE YOU READY FOR THE ULTIMATE CHALLENGE? UNIQUE SYMBIOSIS OF MUSIC AND GRAPHICS | Read more »
Leave Me Alone (Games)
Leave Me Alone 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: 33% off launch sale!!! Somewhere between the 1980s and 1990s there exists a world that never was. A world of skatepunks,... | Read more »
YAMGUN (Games)
YAMGUN 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: The invasion has begun! Protect the walls of the citadel against waves of enemies! But watch out, you will soon run out of ammo...... | Read more »
Chesh (Games)
Chesh 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: It’s like chess, only not at all. ***40% off for a limited time to celebrate our launch!*** Chesh is a game of skill, strategy, luck,... | Read more »

Price Scanner via

Apple restocks refurbished Mac minis for up t...
Apple has restocked Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $... Read more
TP-LINK Next-Gen Routers Support a Large Numb...
TP-LINK, specialists in consumer and business networking products, have announced the availability of Archer C2600, the company’s next-generation router featuring wireless AC, multi-user MIMO, and 4-... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free, and... Read more
Save up to $350 with Apple refurbished iMacs
Apple has Certified Refurbished iMacs available for up to $350 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $1949 $350 off MSRP - 27... Read more
Mac Pros on sale for up to $300 off MSRP
B&H Photo has Mac Pros on sale for up to $300 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2818.99, $181 off MSRP - 3.5GHz 6-core Mac Pro: $3699... Read more
5K iMacs on sale for up to $150 off MSRP, fre...
B&H Photo has the 27″ 3.3GHz 5K iMac on sale for $1899.99 including free shipping plus NY tax only. Their price is $100 off MSRP. They have the 27″ 3.5GHz 5K iMac on sale for $2149, $150 off MSRP... Read more
Twelve South Redesigns BookArc For Today’s Sm...
Twelve South has announced a redesigned version of their very first product, BookArc for MacBook. Tailored specifically for the newest generation of MacBooks, BookArc holds the new, smaller Apple... Read more
Phone 6s Tips & Tricks – Tips Book For iP...
Poole, United Kingdom based Tap Guides Ltd. has announced the release and immediate availability of iPhone 6s Tips & Tricks, an in-depth eBook available in the iBookstore that’s priced just $2.99... Read more
Apple refurbished 2014 13-inch Retina MacBook...
Apple has Certified Refurbished 2014 13″ Retina MacBook Pros available for up to $400 off original MSRP, starting at $979. An Apple one-year warranty is included with each model, and shipping is free... Read more
13-inch 2.5GHz MacBook Pro on sale for $994,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $994.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $105 off MSRP. Price valid... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, you're Read more
*Apple* Solutions Consultant -Bilingual, Chi...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
SW QA Engineer - *Apple* TV - Apple (United...
**Job Summary** The Apple TV team is looking for experienced Quality Assurance Engineers with a passion for delivering first in class home entertainment solutions. **Key Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.