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Tk Listbox problem

by Grygonos (Chaplain)
on Jul 21, 2003 at 17:07 UTC ( #276356=perlquestion: print w/ replies, xml ) Need Help??
Grygonos has asked for the wisdom of the Perl Monks concerning the following question:

I have a listbox setup like so...
#Create the tape removal dialog box my $remove_dialog = $win->DialogBox(-title=>'Choose a tape', -buttons=>["Remove", "Cancel"] +); #Create the listbox to hold the tape numbers my $remove_list = $remove_dialog->Listbox(-width=>'25', -height=>'5', -font=>$font)->pack; #Get the tapes that are stored my @stored_tapes = getTapes(); #Put each tape in the listbox foreach my $tape (@stored_tapes) {$remove_list->insert('end',$tape);} #Show the $remove_dialog box to the user my $remove_result = $remove_dialog->Show; if($remove_result eq "Remove") { my $test = $remove_list->get('active'); print $test; }
This works fine. The problem is ... when I click Remove with nothing selected in the box
$remove_list->get('active')
defaults to the first value in the list. I would like to be able to check for the case of the user not selecting an option.

Does anyone know how this is possible?

Thanks for any help, Gry

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Re: Tk Listbox problem
by bobn (Chaplain) on Jul 21, 2003 at 17:32 UTC

    From perldoc Tk::Listbox, I can only come up with:

    foreach my $tape (@stored_tapes, '<NONE>') {$remove_list->insert('end',$tape);} $remove_list->activate('end'); #Show the $remove_dialog box to the user my $remove_result = $remove_dialog->Show;

    In the absence of selection, returns '<NONE>'. You might want to set -selectmode' to multiple or extended to allow more than one selection at a time.

    --Bob Niederman, http://bob-n.com
      clarification of my previous post.. I want the script to throw an error or prompt for proper input when a user fails to make a selection in the listbox.
      Edit: Thanks for the curselection tidbit. Does anyone know of a better way of reading perldoc on win32... dos shell blows.
        Tk is a standard module with ActiveState, and AS ships HTML docs. Mine is here: D:/Perl/html/site/lib/Tk/Listbox.html. If you're online, try perldoc.com

        That being said, I installed less for windows, changed the background color of my command prompt. Except for the OLE object browser, I don't use the HTML docs any more.

        If Show returns '<NONE>' prompt the user again, thought the curselection() method noted below does look a bit more elegant.

        Also, on my winNT AS 5.6.1 system, perldoc works, if I recall (don't have it here right now). In any event, there shpould be a an item in Start->Programs for ActiveState Perl Documentation, or somethng to that effect.

        --Bob Niederman, http://bob-n.com
Re: Tk Listbox problem
by jsprat (Curate) on Jul 21, 2003 at 17:52 UTC
    Check the return of $remove_list->curselection. curselection returns the number of items selected or an empty string for no selection.

    perldoc Tk::Listbox has more information.

    HTH...

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