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
Credits
About the Author
Acknowledgment
About the Reviewers
www.PacktPub.com
Preface

Creating a widget


The basic method for creating a widget is the same regardless of the widget being created. The differences are in the properties of the widget and if any action can be assigned to it. In the following chapters, we will investigate specific widgets and their properties in depth, but before we reach this point, I would like to introduce you to the button widget and some basic features.

How to do it…

In the following example, we will create a button widget with some basic properties and a single action. Enter the following commands:

1 % button .b text "Exit" command exit
2 % pack .b

At this point, your window should look like the following:

How it works…

The first line instructs the wish shell to create a button named b, which is a child of the parent window identified by the '.' character. This button will have a text label containing the word Exit and it will execute the exit command when clicked. Now click on the button that you have created. You will see that you have exited...