TCL/TK in a Nutshell by Paul Raines, Jeff Tranter

From the Publisher

The Tcl language and Tk graphical toolkit are simple and powerfulbuilding blocks for custom applications. The Tcl/Tk combination is increasingly popular because it lets you produce sophisticated graphical interfaces with a few easy commands, develop and change scripts quickly, and conveniently tie together existing utilities or programming libraries.

One of the attractive features of Tcl/Tk is the wide variety of commands, many offering a wealth of options. Most of the things you'd like to do have been anticipated by the language's creator, John Ousterhout, or one of the developers of Tcl/Tk's many powerful extensions. Thus, you'll find that a command or option probably exists to provide just what you need.

And that's why it's valuable to have a quick reference that briefly describes every command and option in the core Tcl/Tk distribution as well as the most popular extensions. Keep this book on your desk as you write scripts, and you'll be able to find almost instantly the particular option you need.

Most chapters consist of alphabetical listings. Since Tk and mega-widget packages break down commands by widget, the chapters on these topics are organized by widget along with a section of core commands where appropriate. Contents include:

• Core Tcl and Tk commands and Tk widgets
• C interface (prototypes)
• Expect
• [incr Tcl] and [incr Tk]
• Tix
• TclX
• BLT
• Oratcl, SybTcl, and Tclodbc

Product Details

• ISBN: 1565924339
  
• ISBN-13: 9781565924338
• Format: Other Format, 453pp
• Publisher: O'Reilly Media, Incorporated
• Pub. Date: March 1999
• Edition Description: 1976. Corr. 5th Printing ed.
• Sales Rank: 433,962
• Series: In a Nutshell (O'Reilly)

• Table of Contents
• Read a Sample Chapter

Table of Contents

Read a Sample Chapter

Chapter 1: Introduction

What Is Tcl?

One of the attendees at Ousterhout's presentation, Don Libes, saw the applicability of Tcl to a problem he was working on. Within a few weeks he developed the first version of Expect, which became the first killer application for Tcl, driving many people to install Tcl who might have otherwise ignored it.

Ousterhout's philosophy is to embed a scripting language inside applications. Combining the advantages of a compiled language like C (portability, speed, access to operating system functions) with those of a scripting language (ease of learning, runtime evaluation, no compilation) gives an overall reduction in development time and opportunities for creating small, reliable, and reusable software components. An application with an embedded Tcl interpreter can be extended and customized by the end user in countless ways.

The Tcl interpreter has a well-defined interface and is typically built as an object library, making it easy to extend the basic language with new commands. Tcl can also be used as a prototyping language. An application can be written entirely in Tcl, and once the design is proven, critical portions can be rewritten in C for performance reasons.

A year later, at the Winter USENIX conference, Ousterhout presented Tk, a graphical toolkit for Tcl that made it easy to write applications for the X11 windowing system. it also supported the send command, a simple yet powerful way to allow Tk applications to communicate with each other.

Since then, with dozens of Tcl extensions, many of them designed to solve problems related to specific domains such as graphics and relational databases, the Tcl programming environment has become even more powerful. Today, Tcl runs on Unix, Macintosh, and Windows platforms, and even inside a web browser. It has a huge installed base of users and applications, both free and commercial. As Tcl approaches its tenth anniversary, it is poised to continue its growth in popularity.

Structure of This Book

Each language extension chapter follows a similar format: after a brief introduction, any special global and environment variables are described, followed by a logically grouped summary of the commands. The heart of each chapter is an alphabetical summary of each command that lists the options in detail. Short programming examples are provided for the more complex commands.

Chapter 6 covers Expect, the first popular application to be built using Tcl. Chapter 7 is on [incr Tcl], which adds object-oriented programming features to Tcl. Chapter 8 covers [incr Tk], a framework for object-oriented graphical widgets built using [incr Tcl].

Chapter 9 covers Tix, a Tk extension that adds powerful graphical widgets. Chapter 10 is on TclX, also known as Extended Tel, a number of extensions that make Tcl more suited to general-purpose programming. Chapter 11 is on BLT, which provides a number of useful new commands for producing graphs, managing data, and performing other graphics-related functions.

Tcl has good support for relational databases. Chapter 12 and Chapter 13 cover the Tcl extensions for the popular Oracle and Sybase relational databases, and Chapter 14 describes Tclodbc, which supports the Microsoft Windows ODBC database protocol.

Chapter 15, Hints and Tips for the Tcl Programmer, by Tom Poindexter, departs from the style of the rest of the book somewhat by presenting a collection of tips for using Tcl effectively, commonly made errors, and suggestions on programming style.

The Appendix, Tcl Resources, lists further resources on Tcl, both in print and on the Internet. The index cross-references the material in the book, including every Tcl command described in the text.