defaria.com/blogs/Status/archives/000685.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
   2    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
   3 <html xmlns="http://www.w3.org/1999/xhtml" id="sixapart-standard">
   4 <head>
   5    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
   6    <meta name="generator" content="Movable Type 5.2.3" />
   7
   8    <link rel="stylesheet" href="http://defaria.com/blogs/Status/styles-site.css" type="text/css" />
   9    <link rel="alternate" type="application/atom+xml" title="Atom" href="http://defaria.com/blogs/Status/atom.xml" />
  10    <link rel="alternate" type="application/rss+xml" title="RSS 2.0" href="http://defaria.com/blogs/Status/index.xml" />
  11
  12    <title>Status for Andrew DeFaria: CreateWOR: Subclassing TextUndo</title>
  13
  14    <link rel="start" href="http://defaria.com/blogs/Status/" title="Home" />
  15    <link rel="prev" href="http://defaria.com/blogs/Status/archives/000684.html" title="CreateWOR" />
  16    <link rel="next" href="http://defaria.com/blogs/Status/archives/000686.html" title="cqtalk" />
  17
  18    <!--
  19 <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  20          xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/"
  21          xmlns:dc="http://purl.org/dc/elements/1.1/">
  22 <rdf:Description
  23     rdf:about="http://defaria.com/blogs/Status/archives/000685.html"
  24     trackback:ping="http://defaria.com/mt/mt-tb.cgi/72"
  25     dc:title="CreateWOR: Subclassing TextUndo"
  26     dc:identifier="http://defaria.com/blogs/Status/archives/000685.html"
  27     dc:subject="General Dynamics"
  28     dc:description=" Added onChange like callbacks to CreateWOR&apos;s text field and text widget. This required subclassing the TextUndo class and properly handling the call back...."
  29     dc:creator=""
  30     dc:date="2007-10-03T11:17:48-06:00" />
  31 </rdf:RDF>
  32 -->
  33
  34
  35
  36
  37    <script type="text/javascript" src="http://defaria.com/blogs/Status/mt-site.js"></script>
  38 </head>
  39 <body class="layout-one-column" onload="individualArchivesOnLoad(commenter_name)">
  40    <div id="container">
  41       <div id="container-inner" class="pkg">
  42
  43          <div id="banner">
  44             <div id="banner-inner" class="pkg">
  45                <h1 id="banner-header"><a href="http://defaria.com/blogs/Status/" accesskey="1">Status for Andrew DeFaria</a></h1>
  46                <h2 id="banner-description">Searchable status reports and work log</h2>
  47             </div>
  48          </div>
  49
  50          <div id="pagebody">
  51             <div id="pagebody-inner" class="pkg">
  52                <div id="alpha">
  53                   <div id="alpha-inner" class="pkg">
  54
  55                      <p class="content-nav">
  56                         <a href="http://defaria.com/blogs/Status/archives/000684.html">&laquo; CreateWOR</a> |
  57                         <a href="http://defaria.com/blogs/Status/">Main</a>
  58                         | <a href="http://defaria.com/blogs/Status/archives/000686.html">cqtalk &raquo;</a>
  59                      </p>
  60
  61                      <a id="a000685"></a>
  62                      <div class="entry" id="entry-685">
  63                         <h3 class="entry-header">CreateWOR: Subclassing TextUndo</h3>
  64                         <div class="entry-content">
  65                            <div class="entry-body">
  66                               <ul>
  67   <li>Added onChange like callbacks to CreateWOR's text field and text widget. This required subclassing the TextUndo class and properly handling the call back.</li>
  68 </ul>
  69                            </div>
  70                            <div id="more" class="entry-more">
  71                               <h3>Subclassing TextUndo</h3>
  72
  73 <p>This is not working exactly as it should. I can't seem to store things like the onChange callback and a scalar representing the contents of the TextUndo widget in the new MyText object. I rely on overriding the methods InsertKeypress, insert, delete and replace in order to trap when modifications are made to the text, changing the $text member and to call the appropriate callback, but the object that's passed in is different than the object as it was in new and member variables for $text and $modified_CB are missing! So instead I use a package global but this means that only one, the same one, $modification_CB is used for all instantiations of MyText and the $text variable doesn't work at all. Instead one must call get_text in the &$modified_CB:</p>
  74
  75 <div class=code><pre>
  76 # Subclass TextUndo widget to trap and call subroutine when text changes
  77 package Tk::MyText;
  78   use Tk::TextUndo;
  79
  80   use base qw/Tk::TextUndo/;
  81
  82   Construct Tk::Widget "MyText";
  83
  84   my $modified_CB;
  85
  86   sub new {
  87     my $class   = shift;
  88     my $self    = shift;
  89     my %parms   = @_;
  90
  91     $modified_CB        = delete $parms{-modified}      if $parms{-modified};
  92     $self->{text}       = delete $parms{-text}          if $parms{-text};
  93
  94     $class->SUPER::new ($self, %parms);
  95   } # new
  96
  97   sub get_text {
  98     my $self = shift;
  99
 100     return $self->{text};
 101   } # get_text
 102
 103   sub InsertKeypress {
 104     my $self = shift;
 105
 106     $self->SUPER::InsertKeypress (@_);
 107     $self->{text} = $self->get ("1.0", "end");
 108     &$modified_CB ($self) if $modified_CB;
 109   } # InsertKeypress
 110
 111   sub insert {
 112     my $self = shift;
 113
 114     $self->SUPER::insert (@_);
 115     $self->{text} = $self->get ("1.0", "end");
 116   } # insert
 117
 118   sub delete {
 119     my $self = shift;
 120
 121     $self->SUPER::delete (@_);
 122     $self->{text} = $self->get ("1.0", "end");
 123     &$modified_CB ($self) if $modified_CB;
 124   } # delete
 125
 126   sub replace {
 127     my $self = shift;
 128
 129     $self->SUPER::replace (@_);
 130     $self->{text} = $self->get ("1.0", "end");
 131     &$modified_CB ($self) if $modified_CB;
 132   } # replace
 133
 134 </pre></div>
 135                            </div>
 136                         </div>
 137                         <p class="entry-footer">
 138                            <span class="post-footers">Posted by  on October  3, 2007 11:17 AM</span> <span class="separator">|</span> <a class="permalink" href="http://defaria.com/blogs/Status/archives/000685.html">Permalink</a>
 139                         </p>
 140                      </div>
 141
 142
 143                      <div class="trackbacks">
 144                         <h3 id="trackback" class="trackbacks-header">TrackBack</h3>
 145                         <div id="trackbacks-info">
 146                            <p>TrackBack URL for this entry:<br />http://defaria.com/mt/mt-tb.cgi/72</p>
 147                         </div>
 148                         <div class="trackbacks-content">
 149
 150                         </div>
 151                      </div>
 152
 153
 154
 155                   </div>
 156                </div>
 157             </div>
 158          </div>
 159       </div>
 160    </div>
 161 </body>
 162 </html>