Create and place widget from subroutine - tcl

Question

My form is a basic two label frames with one of them containing check boxes and the other is an image. Below these two frames is a back and a start button. The window is preset so that it cannot be altered but when the start button is pressed additional widgets appear on the screen. However, I would like the widgets to only be created and placed on the screen after the checkbox has been selected and the start button has been clicked. The start button then calls a function called "Balanced". Within this code it creates the new widgets and places them on the window. However, it returns an error: "bad window path name '.lblfrmProgress'"
#Set Dual UTA Window as top-level
set UTA .dual_uta
wm state . withdrawn
catch {destroy $UTA}
toplevel $UTA
#Window Properties
wm title $UTA {Device: Dual UTA}
wm maxsize $UTA 522 231 ;#x-500, y-231
wm minsize $UTA 522 231 ;#x-500, y-231
The above is a section of the code that creates a window under the alias of UTA. I thought that this window is the top-level window and as such could be referenced using $UTA.[pathname].
global UTA .dual_uta
#**************** DO NOT MODIFY - USER INTERFACE CODE *******************
#Setup window with labels to show progress
labelframe $UTA.lblfrmProgress -text "Test Progress" -padx 1 -relief groove -height 145 -width 520
label $UTA.lblUTASetup -text "Dual UTA setup according to image"
label $UTA.lblVQuadStart -text "VQuad is initializing"
label $UTA.lblVQTStart -text "VQT is initializing"
label $UTA.lblLMC -text "Load 'Balanced' Master Configuration"
label $UTA.lblTxRx1 -text "Side 1 Tx - Side 2 Rx"
label $UTA.lblTxRx2 -text "Side 1 Rx - Side 2 Tx"
Am I referencing the window variable name incorrectly? Do I need to pass the window variable via procedure call? I just call the file by using 'source Balanced.tcl'
Thanks for the help!

Answer 1

Your use of global appears to be somewhat off. In particular, each argument to global is the name of a variable to map in; initialization should be done separately. Or you can both bring the variable in and (optionally) initialize it with the variable command:
proc whatever {} {
variable UTA .dual_uta
destroy $UTA; # No error if $UTA doesn't exist
toplevel $UTA
wm title $UTA {Device: Dual UTA}
labelframe $UTA.lblfrmProgress -text "Test Progress" \
-padx 1 -relief groove -height 145 -width 520
# Etc.
}
It's usually considered better to use that form of variable only within the enclosing namespace (i.e., the global namespace, ::, unless you say otherwise) and only use the single argument form inside a procedure.
variable UTA .dual_uta
proc whatever {} {
variable UTA
destroy $UTA
toplevel $UTA
wm title $UTA {Device: Dual UTA}
labelframe $UTA.lblfrmProgress -text "Test Progress" \
-padx 1 -relief groove -height 145 -width 520
# Etc.
}
Myself, I'd structure the procedure so that the “root name” of the window hierarchy to build was a parameter to the procedure, binding the name into any callbacks during creation:
proc whatever {UTA} {
destroy $UTA
toplevel $UTA
wm title $UTA {Device: Dual UTA}
labelframe $UTA.lblfrmProgress -text "Test Progress" \
-padx 1 -relief groove -height 145 -width 520
# Etc.
button $UTA.thingamijig -text "Fluffy Bunny" -command [list doTheCallback $UTA]
# ...
}
I'd also be saving the names of widgets in variables for use in later pack/grid calls, so as to avoid having to write long widget paths quite so often. It's just slightly more mnemonic IMO, but certainly not necessary. (Binding the pathnames into callbacks à la the use of list above instead of using a global/namespace variable is better style though, and less problematic than writing callbacks with string substitutions.)

Answer 2

Do you create the UTA variable in a proc? If so, you have to declare it global there too.
The global command takes one or more variable names, so global UTA .dual_uta doesn't make sense.