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Training, Open Source Computer Languages This is page http://www.wellho.net/solutions/tcl-defi ... in-tk.html Our email: info@wellho.net • Phone: 01144 1225 708225 |
| This is now an archive web site. Some is still relevant as at January 2026 but some is purely of historic interest. Lisa and I (Graham) are now fully retired from IT training.We have made many friends over 30 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Apache, Linux and Solaris/SunOS too. Our training notes are out of date, but with upward compatability some examples remain operational and relevant. You are welcome to make use of them "as seen", at your own risk. We now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We remain active, enjoying the times that we are retired but still healthy enough in mind and body to do things! I am also active in many other area and still look after a lot of web sites - you can find an index ((here)) |
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Defining events including variable values in Tk
With Tcl/Tk, you assign an action to a button when you define the button. The action is often specified by the -command option, and it's important to understand the difference between double quotes and braces in this context. If you put the command in DOUBLE QUOTES, then any $ variable used within the command that's to be run will be interpreted using the variable's value at the time that the button is DEFINED. If you put the command in CURLY BRACES, then any $ variable used within the command that's to be run will be interpreted at the time that the button is PRESSED. For example: #!/usr/bin/wish proc action {ff ss} { puts "$ff and $ss" } for {set k 1} {$k<5} {incr k} { button .first$k -text "First $k" -command "action one $k" button .second$k -text "Second $k" -command {action two $k} pack .first$k .second$k } set k 7 All the buttons with "First" text will give different results when pressed - from 1 to 4. The buttons with "Second" text will all give the result 7 when pressed as that's the value that's been left in the variable k when the tcl/tk process enters its main loop. earth-wind-and-fire:~/feb05 grahamellis$ wish wishdemo one and 1 two and 7 one and 2 two and 7 one and 3 two and 7 one and 4 two and 7 earth-wind-and-fire:~/feb05 grahamellis$ See also Tk Events Please note that articles in this section of our
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Related Material
Tcl/Tk - Events in Tk [386] - () [1473] - () [3575] - () [4258] - () resource index - TclTk Solutions centre home page You'll find shorter technical items at The Horse's Mouth and delegate's questions answered at the Opentalk forum. At Well House Consultants, we provide training courses on subjects such as Ruby, Lua, Perl, Python, Linux, C, C++, Tcl/Tk, Tomcat, PHP and MySQL. We're asked (and answer) many questions, and answers to those which are of general interest are published in this area of our site. |
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