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.

Tcl/Tk

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:

http://www.apple.com/downloads/macosx/unix_open_source/tcltk.html

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":

/Applications/Utilities/Wish Shell.app

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
123
() 2 % set b [expr $a * 2]
246
() 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
.b
() 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.

Perl/Tk

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; });
$b->pack();
Mainloop();

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

http://www.cfcl.com/rdm/section7/perltk.html

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 (www.ptf.com), a publisher of books and CD-ROMs for the Free and Open Source software community. Feel free to write to Rich at rdm@ptf.com.

 
AAPL
$119.00
Apple Inc.
+1.40
MSFT
$47.75
Microsoft Corpora
+0.28
GOOG
$540.37
Google Inc.
-0.71

MacTech Search:
Community Search:

Software Updates via MacUpdate

Skype 7.2.0.412 - Voice-over-internet ph...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
HoudahSpot 3.9.6 - Advanced file search...
HoudahSpot is a powerful file search tool built upon MacOS X Spotlight. Spotlight unleashed Create detailed queries to locate the exact file you need Narrow down searches. Zero in on files Save... Read more
RapidWeaver 6.0.3 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
iPhoto Library Manager 4.1.10 - Manage m...
iPhoto Library Manager lets you organize your photos into multiple iPhoto libraries. Separate your high school and college photos from your latest summer vacation pictures. Or keep some photo... Read more
iExplorer 3.5.1.9 - View and transfer al...
iExplorer is an iPhone browser for Mac lets you view the files on your iOS device. By using a drag and drop interface, you can quickly copy files and folders between your Mac and your iPhone or... Read more
MacUpdate Desktop 6.0.3 - Discover and i...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
SteerMouse 4.2.2 - Powerful third-party...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
iMazing 1.1 - Complete iOS device manage...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
PopChar X 7.0 - Floating window shows av...
PopChar X helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to access any font's special characters. Expanded... Read more
OneNote 15.4 - Free digital notebook fro...
OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more

Latest Forum Discussions

See All

Lucha Amigos (Games)
Lucha Amigos 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Forget Ninja Turtles, and meet Wrestlers Turtles! Crazier, Spicier and…Bouncier! Sling carapaces of 7 Luchadores to knock all... | Read more »
Raby (Games)
Raby 1.0.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.3 (iTunes) Description: ***WARNING - Raby runs on: iPhone 5, iPhone 5C, iPhone 5S, iPhone 6, iPhone 6 Plus, iPad Mini Retina, iPad Mini 3, iPad 4, iPad Air,... | Read more »
Oddworld: Stranger's Wrath (Games)
Oddworld: Stranger's Wrath 1.0 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0 (iTunes) Description: ** PLEASE NOTE: Oddworld Stranger's Wrath requires at least an iPhone 4S, iPad 2, iPad Mini or iPod Touch 5th gen... | Read more »
Bounce On Back (Games)
Bounce On Back 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Dwelp (Games)
Dwelp 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: === 50% off for a limited time, to celebrate release === Dwelp is an elegant little puzzler with a brand new game mechanic. To complete a... | Read more »
Make Way for Fat Chicken, from the Maker...
Make Way for Fat Chicken, from the Makers of Scrap Squad Posted by Jessica Fisher on November 26th, 2014 [ permalink ] Relevant Games has announced they will be releasing their reverse tower defense game, | Read more »
Tripnary Review
Tripnary Review By Jennifer Allen on November 26th, 2014 Our Rating: :: TRAVEL BUCKET LISTiPhone App - Designed for the iPhone, compatible with the iPad Want to create a travel bucket list? Tripnary is a fun way to do exactly that... | Read more »
Ossian Studios’ RPG, The Shadow Sun, is...
Ossian Studios’ RPG, The Shadow Sun, is Now Available for $4.99 Posted by Jessica Fisher on November 26th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Mmmm, Tasty – Having the Angry Birds for...
The very first Angry Birds debuted on iOS back in 2009. When you sit back and tally up the number of Angry Birds games out there and the impact they’ve had on pop culture as a whole, you just need to ask yourself: “How would the birds taste... | Read more »
Rescue Quest Review
Rescue Quest Review By Jennifer Allen on November 26th, 2014 Our Rating: :: PATH BASED MATCH-3Universal App - Designed for iPhone and iPad Guide a wizard to safety by matching gems. Rescue Quest might not be an entirely original... | Read more »

Price Scanner via MacPrices.net

Apple Store Black Friday sale for 2014: $100...
BLACK FRIDAY The Apple Store has posted their Black Friday deals for 2014. Receive a $100 PRODUCT(RED) branded iTunes gift card with the purchase of select Macs, $50 with iPads, and $25 with iPods,... Read more
Black Friday: 15% off iTunes Gift Cards
Staples is offering 15% off $50 and $100 iTunes Gift Cards on their online store as part of their Black Friday sale. Click here for more information. Shipping is free. Best Buy is offering $100... Read more
BEVL Releases Dock Tailored for iPhone 6 and...
Seattle based BEVL has released their first product: an iPhone dock that is divergent in build quality, rock-solid function and visual simplicity to complement the iPhone. BEVL is now accepting... Read more
Black Friday: $150 off 13-inch Retina MacBook...
 Best Buy has 13-inch 2.6GHz Retina MacBook Pros on sale for $150 off MSRP on their online store as part of their Black Friday sale. Choose free shipping or free local store pickup (if available).... Read more
Black Friday: $300 off 15-inch Retina MacBook...
 B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for $300 off MSRP as part of their Black Friday sale. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina... Read more
Black Friday: Up to $140 off MacBook Airs, fr...
 B&H Photo has 2014 MacBook Airs on sale for up to $140 off MSRP as part of their Black Friday sale. Shipping is free, and B&H charges NY sales tax only: - 11″ 128GB MacBook Air: $799 $100... Read more
Black Friday: 13-inch 2.5GHz MacBook Pro on s...
 Best Buy has the 13″ 2.5GHz MacBook Pro on sale for $899.99 on their online store as part of their Black Friday sale. Choose free shipping or free instant local store pickup (if available). Their... Read more
Black Friday: 21-inch 1.4GHz iMac on sale for...
 Best Buy has the 21″ 1.4GHz iMac on sale for $899.99 on their online store as part of their Black Friday sale. Their price is $200 off MSRP. Choose free shipping or free local store pick up. Price... Read more
Black Friday iPad Air 2 sale prices, $100 off...
 Best Buy has iPad Air 2s on sale for $100 off MSRP on their online store for Black Friday. Choose free shipping or free local store pickup (if available). Sale prices available for online orders... Read more
2014 1.4GHz Mac mini on sale for $449, save $...
 B&H Photo has the new 1.4GHz Mac mini on sale for $449.99 including free shipping plus NY tax only. Their price is $50 off MSRP, and it’s the lowest price available for this new model. Adorama... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*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* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.