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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

BitTorrent Sync 2.0.82 - Sync files secu...
BitTorrent Sync allows you to sync unlimited files between your own devices, or share a folder with friends and family to automatically sync anything. File transfers are encrypted. Your information... Read more
Google Drive 1.20 - File backup and shar...
Google Drive is a place where you can create, share, collaborate, and keep all of your stuff. Whether you're working with a friend on a joint research project, planning a wedding with your fiancé, or... Read more
Simon 4.0.3 - Monitor changes and crashe...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
Vitamin-R 2.23 - Personal productivity t...
Vitamin-R creates the optimal conditions for your brain to work at its best by structuring your work into short bursts of distraction-free, highly focused activity alternating with opportunities for... Read more
iDefrag 5.0.0 - Disk defragmentation and...
iDefrag helps defragment and optimize your disk for improved performance. Features include: Supports HFS and HFS+ (Mac OS Extended). Supports case sensitive and journaled filesystems. Supports... Read more
PCalc 4.2 - Full-featured scientific cal...
PCalc is a full-featured, scriptable scientific calculator with support for hexadecimal, octal, and binary calculations, as well as an RPN mode, programmable functions, and an extensive set of unit... Read more
FileZilla 3.10.2 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.10.2: Note: Now requires a 64-bit Intel processor.... Read more
The Hit List 1.1.11 - Advanced reminder...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
Bartender 1.2.32 - Organize your menu ba...
Bartender lets you organize your menu bar apps. Features: Lets you tidy your menu bar apps how you want. See your menu bar apps when you want. Hide the apps you need to run, but do not need to... Read more
ClamXav 2.7.5 - Free virus checker, base...
ClamXav is a free virus checker for OS X. It uses the tried, tested, and very popular ClamAV open source antivirus engine as a back end. I hope you like and use ClamXav a lot and that it helps keep... Read more

Protect Yourself from an Onslaught of Ca...
Surprise Attack Games has announced a Cat-astrophic new physics puzzler called Fort Meow! In the game, a young girl named Nia finds her grandfather’s journal which triggers an all mighty feline attack! Why do the cats want the journal? Who knows,... | Read more »
GDC 2015 – Jelly Reef will be Game Oven’...
GDC 2015 – Jelly Reef will be Game Oven’s Last Hurrah, and it Seems like a Good Note to Go Out on Posted by Rob Rich on March 4th, 2015 [ permalink ] It’s sad knowing that Game Oven ( | Read more »
daWindci Deluxe Review
daWindci Deluxe Review By Campbell Bird on March 4th, 2015 Our Rating: :: BLUSTERY PUZZLESUniversal App - Designed for iPhone and iPad This updated puzzle game offers some creative gameplay and new mechanics, but still suffers from... | Read more »
Dungeon Hunter 5 Coming on March 12
Gameloft has excitedly announced that Dungeon Hunter 5 is on its way! Once again, you will adventure across the land of Valenthia exploring dungeons and fighting monsters. The game will have a new asynchronous multiplayer mode called Strongholds... | Read more »
GDC 2015 – The Sandbox 2 is Coming, and...
GDC 2015 – The Sandbox 2 is Coming, and Now it has Textures! | Read more »
Warner Bros. Interactive Announces Mort...
Mortal Kombat X, by Warner Bros. and NetherRealm Studios, will be a a free-to-play fighting/card-battle Mortal Kombat game. The game promises card collecting, multiplayer team combat, classic characters such as Scorpion, Sub-Zero and Raiden, and the... | Read more »
GDC 2015 – Piloteer is Whitaker Trebella...
GDC 2015 – Piloteer is Whitaker Trebella’s Latest Project, and it’s Definitely Something DIfferent Posted by Rob Rich on March 3rd, 2015 [ permalink ] You know | Read more »
PangoLand Review
PangoLand Review By Amy Solomon on March 3rd, 2015 Our Rating: :: COME VISIT PANGO AND FRIENDSUniversal App - Designed for iPhone and iPad PangoLand is an open-ended world full of familiar characters, bright colors and interactive... | Read more »
Knights of Pen & Paper is Leveling U...
With the roll of a die and a critical success, Paradox Interactive has announced Knights of Pen & Paper 2! You’ll be taking your place at the table once again in this sequel to Knights of Pen & Paper +1 Edition. The game will introduce the... | Read more »
GDC 2015 – Project Highrise is an Intere...
GDC 2015 – Project Highrise is an Interesting Idea from SomaSim Posted by Rob Rich on March 3rd, 2015 [ permalink ] You might know SomaSim best from their gold rush sim, 1849< | Read more »

Price Scanner via MacPrices.net

Mac Pros on sale for up to $279 off MSRP
Amazon has Mac Pros in stock and on sale for up to $279 off MSRP. Shipping is free: - 4-Core Mac Pro: $2725.87, $273 off MSRP (9%) - 6-Core Mac Pro: $3719.99, $279 off MSRP (7%) Read more
Sale! 13-inch Retina MacBook Pros for up to $...
B&H Photo has 13″ Retina MacBook Pros on sale for up to $205 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.6GHz/128GB Retina MacBook Pro: $1219.99 save $80 - 13″ 2.... Read more
Another Tranche Of IBM MobileFirst For iOS Ap...
IBM has announced the next expansion phase for  its IBM MobileFirst for iOS portfolio, with a troika of new apps to address key priorities for the Banking and Financial Services, Airline and Retail... Read more
Sale! 15-inch Retina MacBook Pros for up to $...
B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for up to $250 off MSRP for a limited time. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $... Read more
WaterField Designs Introduces the Minimalist...
With Apple Pay gaining popularity, Android Pay coming in May 2015, and loyalty cards and receipts that can be accessed from smartphones, San Francisco’s WaterField Designs observes that it may be... Read more
Sale! 15-inch 2.2GHz Retina MacBook Pro for $...
 Best Buy has the 15″ 2.2GHz Retina MacBook Pro on sale for $1774.99 $1799.99, or $225 off MSRP. Choose free home shipping or free local store pickup (if available). Price valid for online orders... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $170 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz... Read more
13-inch 2.5GHz MacBook Pro on sale for $100 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999.99 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more
27-inch 3.5GHz 5K iMac in stock today and on...
 B&H Photo has the 27″ 3.5GHz 5K iMac in stock today and on sale for $2299 including free shipping plus NY sales tax only. Their price is $200 off MSRP, and it’s the lowest price available for... Read more
Apple Launches Free Web-Based Pages and Other...
Apple’s new Web-only access to iWork productivity apps is a free level of iCloud service available to anyone, including people who don’t own or use Apple devices. The service includes access to Apple... Read more

Jobs Board

*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
*Apple* Pay Automation Engineer - iOS System...
**Job Summary** At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring passion and dedication to your job Read more
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Event Director, *Apple* Retail Marketing -...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global engagement strategy and team. Delivering an overarching brand Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.