Tcl/Tk: An introduction D. Kim, K. Kundu, and M. Siegel

Tcl/Tk: An introduction

D. Kim, K. Kundu, and M. Siegel

November 26, 2002CMSC 631

November 26, 2002

Tcl/Tk: An Introduction 2

Tcl (Tool Control Language) history

Developed in late 1980s by John Ousterhout at UC Berkeley

Created as a single language used to control IC tools, rather than use a different language for each one.

Provides for extensions such as Tk (GUI), [incr Tcl] (OOP), etc.

November 26, 2002


8.0 Aug8.0 Aug

Timeline of Tcl

1988 1989 1990 1991 1992 1993 1995 1997 1998

2. Open source distributionsfrom U.C. Berkeley:

• Easy GUIs under Unix• Extensible applications

2. Open source distributionsfrom U.C. Berkeley:

• Easy GUIs under Unix• Extensible applications

3. Tcl enhanced at Sun Microsystems:• Windows, Macintosh ports• Web/Internet support• Java support

3. Tcl enhanced at Sun Microsystems:• Windows, Macintosh ports• Web/Internet support• Java support

4. Scriptics formed:• Evolve and extend Tcl platform• Create development tools

4. Scriptics formed:• Evolve and extend Tcl platform• Create development tools

1. Tcl created as general-purpose command/scripting language by John Ousterhout

1. Tcl created as general-purpose command/scripting language by John Ousterhout

1994 19991996 2000 2001

7. ActiveState introduces Tcl support and services

7. ActiveState introduces Tcl support and services

6.0 Sept6.0 Sept 7.0 Sept7.0 Sept 7.4 July7.4 July 7.6 Oct7.6 Oct 8.1 Apr8.1 Apr

8.2 Aug8.2 Aug

8.3 Feb8.3 Feb

……

Slide courtesy of ActiveState

November 26, 2002


Installing Tcl/Tk

Windows/Mac: Latest distribution maintained by ActiveState (ActiveTcl 8.4.1.0). Download at http://www.tcl.tk/

Unix/Linux: Tcl/Tk is included with most Unix/Linux distributions

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3 Ways to Use Tcl/Tk1. tclsh for interactive use

$ tclsh% puts “I am using tclsh”I am using tclsh

2. wish for programs using the Tk package

3. Embed in C program with <tcl.h>

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Basics Tcl script =

Sequence of commands. Tcl command =

One or more words separated by white space.

First word is command name, others are arguments.

Returns string result. Example:

set a 22set b 33

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[ ] and $ substitution

Substitutions: variable substitution: set id 631puts “This class is CMSC $id”

command substitution, evaluated as separate script:set b [expr $id*4]

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Math Evaluation expr command evaluates expressions.

Sample command Resultset b 5 5expr ($b*4)-3 17expr $b <= 2 0

Many other math functions included, such as sin, cos, sqrt, and log.

November 26, 2002


Conditional/Looping Statements Like most languages, Tcl supports an if

statement, though the keywords then and else are optional.

For loop: for {set a 0} {$a < 100} {incr a} {

#more code here

}

While loop is also supported

November 26, 2002


Tcl lists list are ordered collections of elements any proper list can also be a Tcl

command (eval) concat list list – concatenate lists

concat {a b c} {d e f} a b c d e f join list sep – convert to string with

separatorjoin {a b c} ", " a, b, c

Some list functions: lappend lindex, linsert, llength, lrange

November 26, 2002


Tcl Arrays Tcl arrays are 'associative arrays': index

is any string set nicholas(1) 331 set nicholas(2) [expr $nicholas(1) + 300] array names nicholas

Matricies can be “faked” with index notation:

set A(1,1) 10 set A(1,2) 11 array names A

=> 1,1 1,2 (commas included in names!)

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Regular Expressions Tcl has full support for regular

expression pattern matching and substitution

regexp command for matching, places matched chars into variable specified

regsub for substitution

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Tk : An Introduction Tk is a Toolkit for programmable

user interfaces. Tk provides a set of Tcl commands

that create and manipulate widgets. John Ousterhout began work on Tk

in late 1988; finished in 1990. Tk's GUI facilities were both very

simple and very powerful.

November 26, 2002


Tk : Widgets

A widget is window in a GUI with particular appearance and behavior.

Widget types include buttons, scrollbars, menus, and text windows.

Tk also has a general purpose drawing widget called a canvas that lets you create lightweight items such as lines, boxes and bitmaps.

November 26, 2002


Tk : Widgets (Con’t)

Tk widgets organized in a hierarchy. - children windows inside a parent window

Parent widgets use frame widgets to lay the children windows out

Can create complex windowing schemes using Tk widget hierarchy.

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Tk : Geometry Manager Widgets are under the control of

geometry manager that controls their size and location on the screen

Until the GM learns about a widget, it is not mapped onto a screen

Types of Geometry Managers: The Pack GM The Grid GM The Place GM

November 26, 2002


Tk : A Small Example

#!/usr/local/bin/wish

button .hello -text Hello -command {puts stdout "Hello World!"}

pack .hello -padx 20 -pady 10

(code courtesy of Practical Programming in Tcl and Tk by Brent B. Welch)

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Tk : Events

Tk-based application has event-driven control flow.

Usually Tk widgets handle most events automatically.

For specialized behavior, bind command is used.

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Tk : Events (Con’t) Examples of events include mouse motion,

mouse clicks, keystrokes, window resizing, window destruction

Virtual events like cut and paste are also possible.

Event bindings grouped into classes called bindtags which are associated with a class.

Focusing on windows helps switch bindtags.

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Example – diff command

#!/usr/bin/wish

# Description :# this program will give the user a graphical interface to the Unix# command "diff". The window will allow the user to specify a pair# of files to check for differences and a few options, as well as# colorizing the output appropriately

# title

wm title . tkdiff

November 26, 2002


Example: (Con’t)

# frame for the first file

frame .first -borderwidth 1label .first.name1 -text "Filename 1:" -foreground redentry .first.ent1 -width 68 -relief sunken \ -textvariable name1pack .first.name1 -side leftpack .first.ent1 -side left -fill x -expand true

November 26, 2002


Example: (Con’t)

# frame for the second file

frame .second -borderwidth 0label .second.name2 -text "Filename 2:" -foreground blueentry .second.ent2 -width 68 -relief sunken \ -textvariable name2pack .second.name2 -side leftpack .second.ent2 –side left -fill x -expand truepack .first .second -fill both

November 26, 2002


Example: (Con’t)

# frame for check boxes

set third [frame .third -borderwidth 2]checkbutton $third.1 -text "Ignore Case Changes" \ -variable cFlagcheckbutton $third.2 -text "Ignore Whitespace Diffs" \ -variable wFlagpack $third.1 $third.2 -side leftpack $third -fill x

November 26, 2002


Example: (Con’t)

# frame for command buttons

set fourth [frame .four -borderwidth 2]button $fourth.1 -text Quit -command Exit$fourth.1 config -activebackground redbutton $fourth.2 -text Go -command Run$fourth.2 config -activebackground greenbutton $fourth.3 -text Clear -command Clear$fourth.3 config -activebackground bluepack $fourth.1 $fourth.2 $fourth.3 -side leftpack $fourth

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Example: (Con’t)

# frame for display area

frame .msg -borderwidth 2set box [text .msg.box -width 60 -height 10 \ -borderwidth 1 -relief raised -setgrid true \ -yscrollcommand {.msg.yscroll set} \ -xscrollcommand {.msg.xscroll set}]scrollbar .msg.yscroll -command {.msg.box yview} \ -orient verticalscrollbar .msg.xscroll -command {.msg.box xview} \ -orient horizontalpack .msg.yscroll -side right -fill ypack .msg.xscroll -side bottom -fill xpack .msg.box -side left -fill both -expand truepack .msg -side top -fill both -expand true

November 26, 2002


Example: (Con’t)

# for change colars

.msg.box tag configure TagA -foreground red

.msg.box tag configure TagB -foreground blue

# when user click exit buttonproc Exit {} { set picked [tk_messageBox -type yesno \ -message "Really Quit?" \ -default no \ -icon question] if {$picked == "yes"} { exit }}

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Example: (Con’t)

# when user click go buttonproc Run {} { global box name1 name2 cFlag wFlag input if {$wFlag == 1 && $cFlag == 1} { set cmd "diff $name1 $name2 -c -w" } elseif {$wFlag == 1 && $cFlag == 0} { set cmd "diff $name1 $name2 -w" } elseif {$wFlag == 0 && $cFlag == 1} { set cmd "diff $name1 $name2 -c" } else { set cmd "diff $name1 $name2“ } if [catch {open "|$cmd |& cat"} input] { $box insert end $input\n } else { fileevent $input readable Log $box insert end $cmd\n }}

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Example: (Con’t)

# function for write a log to display areaproc Log {} { global input box if [eof $input] { Stop } else { gets $input line if [regexp "^<" $line matches] { $box insert end $line\n TagA } elseif [regexp "^>" $line matches] { $box insert end $line\n TagB } else { $box insert end $line\n } $box see end }}

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Example: (Con’t)

# when input file is end of fileproc Stop {} { global input box catch {close $input}}

# clear the display areaproc Clear {} { global box $box delete 1.0 end}

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Example: Run

November 26, 2002


Example: Output

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Tcl/Tk: An introduction D. Kim, K. Kundu, and M. Siegel

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