Hi!
I'm messing with the .trace() function of StringVar()s to, in this case, check
to see that the user has not entered more than an allowable number of
characters (ckW() below does that). I'm replacing a monstrous <KeyRelease>
.bind method.
I'm using the line below and it seems to work fine, but I'm not sure I
understand it. lambdas really make my head hurt. Var is a global StringVar()
(the line below is in a function of mine that I call to create a
Label():Entry() pair of widgets, like "Barcode: ___________"). A form
(Toplevel with Entry() fields on it) with an Entry() associated with a
StringVar() may be destroyed and brought up multiple times over the course of
using the program, so the .trace() may be applied to a given StringVar()
multiple times. Is that a problem? Do these calls "stack up", or does one
identical .trace() cancel the previous one? In case they do stack up I wanted
to do a trace_vdelete() right before this .trace line, but I can't get it
right. Do I need to do it? If so, how?
...
[Var.trace_vdelete here?]
Var.trace("w", lambda nm, idx, mode, var = Var: ckW(var, Max))
...
Thanks!
Bob
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