Question

I am trying the validate the text input of an entry.

entry $w.e -validate key -vcmd "entryChanged $w.l $w.e"

I have the following callback defined.

proc entryChanged {l e} {
    puts [$e get]
    return 1
}

The problem is that get returns the previous value of the entry as the new value isn’t set until after the validation. My question is how do I access the new value? (value to be validated) I believe it has something to do with -textvariable, however, I can’t find much documentation on this.

Answer 1

You’ll want to have a good read through the Validation section of the entry documentation. For example, try this

... -vcmd {entryChanged  %W %s %P}

proc entryChanged {widget_name old_value new_value} {
    puts "widget name = $widget_name"
    puts "previous value = $old_value"
    puts "edited value = $new_value"
    return true
}