Mastering Perl/Tk

The HList Family of Widgets

The HList widget is the basis for the two other Tix widgets we are examining: Tree and DirTree. The HList widget is a hierarchical list that uses the idea of paths to create the hierarchy it displays. You could also display a flat hierarchy and use HList as a type of Listbox that can have columns and column headings. Tree and DirTree are specialized versions of HList. DirTree is used to display a directory structure from a given starting point. All three of the widgets use display items.

The simplest way to use the HList widget is similar to a Listbox or TList. Create it and then add items to it:

use Tk;
use Tk::HList;
my $mw = MainWindow->new(-title => 'HList');

my $hlist = $mw->HList->pack;
foreach (qw/one two three four five/) {
  $hlist->add($_, -text => $_);
}
MainLoop;

Looking at this example, it isn’t obvious at all that you can have display items or styles with an HList. The only non-self-explanatory item (given that you understand Listbox) is the first argument to the add method, which is a path. Since this example doesn’t take advantage of any of the special hierarchical features of the HList, we’re not going to bother showing a screenshot yet.

Just like a Listbox, the HList contains a list of entries. Each time you call the add method, you create another entry in the list. Each entry can contain one or more display items. If you want more than one display item with each entry, use the -columns option. Unlike TList, which automatically manages ...