Dear Monks,
In many applications I see 'Undo' feature. For example Microsoft Word or Photoshop or even Emacs editor. How I can achieve the similar effect in Perl? For example see the following code.

#!/usr/local/bin/perl
use Data::Dumper;
my $hash = { a => 21, b => 32, c => 43 };
my $array = [ 11,12,13,14];

foreach (1..3){
    perform_operationX();
    print_data();
}

cancel_last_operationX(2);

sub perform_operationX {
    my $letter = chr(97+ int rand(10));
    my $number = int rand(100);
    $hash->{$letter} = $number;
    shift @$array;
}

sub print_data{
    print Dumper($hash,$array);
}

sub cancel_last_operationX {
    my $number_of_operations =  shift;
    ......... UNDO CODE .............

}

[download]
In order to achieve this if we have to save the state of the previous operation how do we do it? An reading/code/material/module etc would be useful.

Thank You
{Artist}

In reply to Undo Operations by artist

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.