This is a followup to yesterday's question on users entering MAC addresses. I need an entry widget to do the following:
1) Accept 1-2 hex digits.
2) If a digit is wrong don't let the user exit the widget
3) Flash the background red when the entry is wrong
4) Be nice to automatically jump to the next widget when 2 valid hex digits have been entered.

This is an example of what I have now. 

#!perl  -w  -d

use strict;
use Tk;

my $addy1 = '32';
my $addy2 = '42';

my $mw = MainWindow->new();

$mw->Entry( -textvariable    => \$addy1,
            -width           => 2,
            -validate        => 'focusout',
            -validatecommand => sub{
                                    # debugging, print the field.
                                    printf"<<%s>:%d\n", $_[0], 
                                          $_[0] =~ /^[0-9a-f]{1,2}$/i;
                                    $_[0] =~ /^[0-9a-f]{1,2}$/i;},
            -invalidcommand  => sub{$mw->bell},
          )->pack(-side => 'left');

# Need a field to go to so 'focusout' can happen.
$mw->Entry( -textvariable    => \$addy2,
            -width           => 2,
            -validate        => 'focusout',
            -validatecommand => sub{
                                    # debugging, print the field.
                                    printf"<<%s>:%d\n", $_[0], 
                                          $_[0] =~ /^[0-9a-f]{1,2}$/i;
                                    $_[0] =~ /^[0-9a-f]{1,2}$/i;},
            -invalidcommand  => sub{$mw->bell},
          )->pack(-side => 'left');
MainLoop;

[download]

In reply to Entry widget questions by snotnose

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.