2dfe Tk locks up - 100% c.p.u. on a simple program (Tcl, Perl, Python)
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Tk locks up - 100% c.p.u. on a simple program (Tcl, Perl, Python)

Fighting packs and grids - Tk under Tcl, Perl, Python

You'll use pack OR grid to place components into your frame in a Tcl/Tk application. You may use both pack and grid within the same program, but NOT within the same frame. If you do, not only will you be writing code that has no clear meaning, but you'll also invoke the pack and grid handlers at the same time and may cause them to fight. Have a look at this code:

button .ouch -text "do NOT press this button" -command exit
label .more -text "This is a label"
 
button .wow -text "This is a button you may press" -command exit
label .contd -text "Another BORING! label"
 
grid .more .ouch
pack .ouch .more
pack .contd .wow
grid .wow .contd

When I ran that, my prompt was lost, no wish window appeared, and my c.p.u. utilisation rocketed to 99% ... and stayed there. I guess when you have two individuals fighting, they don't show any regard at all for others around them.

Footnote I've often contended that the way to get a user to select a button is to label it "Do not push this under any circumstances" ... which is what I have put in the example above. Some may say that I have a warped sense of humour, or that I have watched too much "Trigger Happy TV".
(written 2007-09-09, updated 2007-09-11)

 
Associated topics are indexed under
P307 - Perl/Tk
  [3009] Expect in Perl - a short explanation and a practical example - (2010-10-22)
  [1310] Callbacks - a more complex code sandwich - (2007-08-19)
  [738] (Perl) Callbacks - what are they? - (2006-05-30)
  [599] Perl/Tk real time display - (2006-02-10)
  [596] The magic of -textvariable - (2006-02-08)
  [595] Add a friendly front end with Tk - (2006-02-08)

T218 - Tcl/Tk - Geometry Managers
  [1470] fill and expand on Tcl/Tk pack command - (2007-12-13)
  [1335] Expanding a grid - Tcl/Tk - (2007-09-07)
  [787] Tk - laying out your GUI with frames, pack and grid - (2006-06-30)
  [445] Sticky news - (2005-09-15)
  [212] Tcl/Tk (wish) Grid layout example - (2005-02-12)

Y205 - Further uses of Python
  [1663] Python in an afternoon - a lecture for experienced programmers - (2008-06-01)
  [1036] Python Qt, wX, TkInter, and Jython - training?? - (2007-01-16)
  [745] Python modules. The distribution, The Cheese Shop and the Vaults of Parnassus. - (2006-06-05)
  [190] Python engines - (2005-01-26)


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