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

Joining two lists


Now that we have seen how to make a list we will explore combining lists. To accomplish this, Tcl provides the concat command. The syntax is as follows:

concat value1 value2 …

How to do it…

In the following example, we will concatenate a set of lists containing single characters. Return values from the commands are provided for clarity. Enter the following command:

% concat {a b c} {1 2 3}
a b c 1 2 3

How it works…

The concat command joins each of its arguments together with spaces after first trimming all leading and trailing whitespace, and in the case of a list, the results will be flattened. Although this command will concatenate any arguments provided, we will be focusing on its usage as it applies to the list elements. To denote that a list is being provided as the argument, it should be encased within braces {}. This is another method of providing lists. They may also be passed as named list variables, actual list commands, or within quotes. If no arguments are provided...