Effective Tcl/Tk Programming Writing Better Programs with Tcl and Tk

You need a graphical user interface, and it needs to run on multiple platforms. You don't have much time, and you're not a wizard with X/Motif, the Win32 GUI, or the Mac GUI. The project seems impossible, but with Tcl/Tk it's simple and fun. The Tcl scripting language and the Tk toolkit create a powerful programming environment for building graphical user interfaces. With two lines of code you can create a simple button; with two hundred lines of code, a desktop calculator; and with a thousand lines of code, an industrial-strength groupware calendar and appointment minder. Your applications run on all of the major platforms: UNIX, Windows 95/NT, and Macintosh. You can even embed your programs in a Web page to make them available online. Mark Harrison and Michael McLennan, two noted Tcl/Tk experts, combine their extensive experience in this practical programming guide. It is ideal for developers who are acquainted with the basics of Tcl/Tk and are now moving on to build real applications. Effective Tcl/Tk Programming shows you how to build Tcl/Tk applications effectively and efficiently through plenty of real-world advice. It clarifies some of the more powerful aspects of Tcl/Tk, such as the packer, the canvas widget, and binding tags. The authors describe valuable design strategies and coding techniques that will make your Tcl/Tk projects successful. You will learn how to: bull; bull;Create interactive displays with the canvas widget bull; Create customized editors with the text widget bull;Create new geometry managers, like tabbed notebooks or paned windows bull;Implement client/server architectures bull; Handle data structures bull; Interface with existing applications bull;Package Tcl/Tk code into reusable libraries bull; Deliver Tcl/Tk applications that are easy to configure and install bull; Embed applications in a Web page bull; Build applications that will run on multiple platforms Throughout the book, the authors develop numerous applications and a library of reusable components. Learn from their approach, follow their strategies, and steal their code for your own applications! But don't bother retyping all of the examples. 0201634740B04062001

Mark Harrison has been programming in Tcl ever since he heard John Ousterhout speak at the 1990 Usenix conference.* He currently works in the telecommunications industry for DSC Communications Corporation as a senior system architect, where he is Chief Tcl Evangelist.* In addition, he is enrolled in the computer science department at the University of Texas at Dallas.

Michael J. McLennan is a Distinguished Member of Technical Staff at Bell Labs Innovations for Lucent Technologies, where he develops software for Computer-Aided Design (CAD). He has been a Tcl/Tk enthusiast since 1992, writing many extensions and applications. He developed the incr Tcl extension, which adds object-oriented facilities to Tcl/Tk. He has also created several Tcl/Tk training courses.

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Preface It's easy to get started with Tcl/Tk. Just follow the steps in Appendix A to obtain the wish program and start it up. Then type in a few lines of code, like this: %button .b -text "Hello, World!" -command exit=> .b%pack .b You'll see theHello, World!button appear as soon as you enter the pack command. On Windows 95, it will look like this:You don't have to edit any makefiles or fight with a compiler. You don't need to know everything about the X window system or the Microsoft Foundation Classes. You don't need to wade through pounds of confusing documents to find symbols, such as XA_FONT_NAME . Instead, you type a few lines of Tcl code and immediately see the results.As you learn more about the Tk widgets, you can write lots of simple programs. With a text widget and 100 lines of Tcl code, you can put together a program for sending electronic mail (e-mail) messages. With a canvas widget and 200 lines of Tcl code, you can create a simple drawing editor.A few other Tcl/Tk books will help you get started. John Ousterhout's Tcl and the Tk Toolkit starts with a complete overview of the Tcl language and then goes on to describe each of the Tk widgets. The book even describes how to add new functionality to Tcl/Tk by integrating your own C code into the wish program. Brent Welch's book Practical Programming in Tcl and Tk is another good source of Tcl/Tk code examples.After reading one of the introductory Tcl/Tk books, you will be well acquainted with the nuts and bolts. But you may not have a good understanding of how they fit together to make an application.We wrote this book to pick up where the others leave off. We assume that you understand some of the Tcl language and that you've written a few simple Tcl/Tk programs. If not, you can pick it up as you read along. But instead of explaining the basics, we focus on areas that are commonly misunderstood-such as the pack command, the bind mechanism, and the canvas widget. We not only explain how these things work but also show how you can use them to build powerful applications. We explain how the packer works and then show how you can use it to create a tabbed notebook that displays "pages" of widgets. We explain how binding tags work and then show how you can use them to handle the modes in a drawing editor. We explain how the canvas works and then show how you can use it to build a progress gauge, a color wheel, and a calendar.Along the way, we describe the lessons that we've learned from developing many thousands of lines of Tcl/Tk code. We show you software architectures and programming techniques that will make your Tcl/Tk code easier to maintain. For example, we show how to Create client/server applications Package Tcl/Tk code into libraries of reusable components Use lists and arrays as data structures Handle common quoting problemsAbove all else, we try to present a holistic view of application development. In Chapter 1, we show you how to go about designing an application--from the initial concept to a working prototype to a finished product. Throughout the book, we develop several useful applications: a desktop calculator, a drawing editor, and a daily calendar that will store all of your appointments. In Chapter 8, we show you how to add polish to your finished applications and how to deliver them to customers.In the course of this book, we develop more than two dozen useful components, including a toolbar, a paned window, a balloon help facility, and a confirmation dialog. We provide complete source code for these components in the software that accompanies this book. You can download this software from th