character limited edit control

[Guest_imported]

I have an edit box in a VTcl app that needs to be limited to a certain number of characters. Is there a predefined way to handle this where when the number is met, the next keyboard stroke is a beep and prevents the character from being entered.

Thanks.

 

[AviaTraining]

Check out my response in thread287-311673, "Disable frame and limit entry." It describes a couple of techniques for limiting the number of characters that the user can enter into an entry widget.

A simpler method might be to create a binding on the entry for <KeyPress> events. You could check to see if the result of the <KeyPress> would exceed the limits of the entry, and if so, to execute a break command to stop the propagation of the event to the Entry class bindings (which handle actually inserting the character into the widget). Something along the lines of:

set max 6  ;# Or whatever limit
bind .e <KeyPress> {
  if {![string equal {} %A]
      && [string is print %A]
      && ([%W index end] >= $max)} {
    break
  }
}

The downside to this approach is that it doesn't prevent a user from copying a chunk of text that exceeds the limits and then pasting it into the entry. The other approaches I describe in the link above do handle that problem. - Ken Jones, President, ken@avia-training.com
Avia Training and Consulting,

http://www.avia-training.com

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