Book Image

Tcl/Tk 8.5 Programming Cookbook

Book Image

Tcl/Tk 8.5 Programming Cookbook

Overview of this book

With Tcl/Tk, you can create full-featured cross-platform applications in a simple and easy-to-understand way without any expensive development package; the only tools required are a simple text editor and your imagination. This practical cookbook will help you to efficiently interact with editors, debuggers, and shell type interactive programs using Tcl/Tk 8. This cookbook will comprehensively guide you through practical implementation of Tcl/Tk 8.5 commands and tools. This book will take you through all the steps needed to become a productive programmer in Tcl/Tk 8. Right from guiding you through the basics to creating a stand-alone application, it provides complete explanation of all the steps along with handy tips and tricks. The book begins with an introduction to the Tcl shell, syntax, variables, and programming best practices in the language. It then explores procedures and the flow of events with control constructs followed by advanced error trapping and recovery. From Chapter 4, a detailed study of string expressions and handling enables you to handle various string functions and use lists to expand the string functionality. The book then discusses in-depth the Tcl Dictionary and how to utilize it to store and retrieve data. File operations and Tk GUI handling are covered extensively along with a developing a real-world address book application to practice the concepts learned.
Table of Contents (20 chapters)
Tcl/Tk 8.5 Programming Cookbook
About the Author
About the Reviewers

Writing to the console

Although rarely used in live programs, the console is a valuable tool during initial development. It allows us to direct debugging information easily, without requiring the overhead of creating dialog boxes (covered later in this book). To allow us to display a console on systems that have no console, or to reveal a hidden console, Tcl provides the console command. The console command accepts four keywords as follows:



eval script

Evaluate the script argument as a Tcl script within the console interpreter.


Hide the console.


Display the console.

title string

Query OR modify the console title.

The syntax is as follows:

console keyword argument

How to do it…

In the following example, we will hide the console and then create a set of buttons to display the console and to write a message. Enter the following commands:

1 % button .b text "Show Console" command {console show}
2 % button .c text "Message" command {puts "My Message...