This Tk application uses a while infinite loop. Upon each iteration,
it checks a boolean variable that I can toggle with a key binding.
If the value is 0, the loop continues but does nothing because of
the first line:

if {$::GO == 0} {continue}

The activity stops as expected, but then it becomes unresponsive.
I can't untoggle, I can't do anything.

What is the correct way of doing what I want?

--
Luc
>>

* Luc <no@no.no>
| This Tk application uses a while infinite loop. Upon each iteration,
| it checks a boolean variable that I can toggle with a key binding.
| If the value is 0, the loop continues but does nothing because of
| the first line:
>
| if {$::GO == 0} {continue}
>
| The activity stops as expected, but then it becomes unresponsive.
| I can't untoggle, I can't do anything.

That's because mouse clicks are handled by the event loop.
Losely spoken, the event loop runs only if there is nothing else to do,
and cleary the above tight loop is "something" to do ;-)

| What is the correct way of doing what I want?

Check 'vwait' or 'tkwait variable' if you want to wait for a variable to
be set while the GUI stays responsive:
https://www.tcl.tk/man/tcl/TclCmd/vwait.html
https://www.tcl.tk/man/tcl/TkCmd/tkwait.html

or 'update' if you need to give the GUI a go during a runnning calculation
https://www.tcl.tk/man/tcl/TclCmd/update.html
(but be aware of
https://wiki.tcl-lang.org/page/Update+considered+harmful
)

HTH
R'

At Tue, 13 Dec 2022 11:18:09 +0100 Ralf Fassel <ralfixx@gmx.de> wrote:

>
> * Luc <no@no.no>
> | This Tk application uses a while infinite loop. Upon each iteration,
> | it checks a boolean variable that I can toggle with a key binding.
> | If the value is 0, the loop continues but does nothing because of
> | the first line:
> >
> | if {$::GO == 0} {continue}
> >
> | The activity stops as expected, but then it becomes unresponsive.
> | I can't untoggle, I can't do anything.
>
> That's because mouse clicks are handled by the event loop.
> Losely spoken, the event loop runs only if there is nothing else to do,
> and cleary the above tight loop is "something" to do ;-)
>
> | What is the correct way of doing what I want?
>
> Check 'vwait' or 'tkwait variable' if you want to wait for a variable to
> be set while the GUI stays responsive:
> https://www.tcl.tk/man/tcl/TclCmd/vwait.html
> https://www.tcl.tk/man/tcl/TkCmd/tkwait.html
>
> or 'update' if you need to give the GUI a go during a runnning calculation

Specificly, "update idletasks" should be included in any "loop" in a Tk
application:

while {sometest} {
some processing...
update idle
}

> https://www.tcl.tk/man/tcl/TclCmd/update.html
> (but be aware of
> https://wiki.tcl-lang.org/page/Update+considered+harmful
> )

"update idletasks" is generally "safe". This limits the event loop to
necessary "idle" tasks.

>
> HTH
> R'
>
>

--
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Deepwoods Software -- Custom Software Services
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Luc <no@no.no> wrote:
> This Tk application uses a while infinite loop.

Why? That will block the event loop from running.

> Upon each iteration, it checks a boolean variable that I can toggle
> with a key binding. If the value is 0, the loop continues but does
> nothing because of the first line:
>
> if {$::GO == 0} {continue}
>
> The activity stops as expected, but then it becomes unresponsive.
> I can't untoggle, I can't do anything.

Your description seems reversed. Once the 'infinite loop' starts, then
the UI should become unresponsive.

> What is the correct way of doing what I want?

Tell us what "you want to do" -- then we can answer with better
answers.