listbox refresh with Tk::After

hudo has asked for the wisdom of the Perl Monks concerning the following question:

Hello, I'd like to display the contents of a file in a TK listbox. The contents of the listbox should be refreshed automatically after n seconds. I saw the method Tk::After but I don't know how to use it. Maybe somebody can help me with the syntax or even knows other methods for the automatic refresh. Here is the code:


#!/usr/bin/perl

use Tk;
use Tie::File;
use Tk::after;


my $liste;
my $liste_font;
my $breite=100; ### Anzahl der abgezeigten Zeichen in der Liste
my $the_selectmode = "extended";  ### "single","multiple","extended"
my $enter;
my @array_file;



my $mw = MainWindow->new();

### rahmen fuer Hauptseite 
my $frame1 = $mw->Frame(-width=>50, -height=>50, -bg=>"seashell");
my $frame2 = $mw->Frame(-width=>5, -height=>5, -bg=>"grey80");

$liste_font = $mw->fontCreate(-family=>"courier", -size=>7  );        
+### zB treffer-Liste

my $liste = $frame1->ScrlListbox(

        ##-font=>$liste_font,
        -setgrid=>1,
        -scrollbars=>"se",
                #-background=>"wheat3",
                -background=>"lemonchiffon3",
                -borderwidth=>3,
                -highlightthickness=>10,
                ##-selectmode => "extended",  ###"multiple"
                ##-selectmode => "multiple",
                ##-selectmode => "single",   
            ##    -selectmode =>$the_selectmode,
                -height => 30,
        ##        -width => $breite,
                -selectforeground=>"blue",
                -selectbackground=>"green",
                ##-setgrid=>1,
                ##-selectborderwidth=>1,
                -relief=>"ridge",
                -exportselection => 1)->pack(-side=>"right", -expand=>
+1, -fill=>"both");

my $exitButton     = $frame2->Button ( -text=>"Schliessen" ,-command=>
+"exit" ,-bg=>"red" ,-activebackground=>"red" ,-activeforeground=>"cya
+n" )->pack(-anchor=>"w" ,-padx=>10  ,-pady=>15  ,-ipady=>10 ,-fill=>"
+x");
 


##################################################################
### Packen der Rahmen auf Hauptseite  ############################
##################################################################


$frame1->pack(-side => 'left' ,-expand=>1 ,-fill=>"both");
$frame2->pack(-side => 'right',-expand=>1 );

$frame2->pack(-expand=>1 ,-fill=>"both");


##############################################
### sofort ausgefuehrte Subroutines 
##############################################
=pod
while(1) {
    
    #&fill_from_file();


    sleep(2);
};
=cut


#&fill_from_file();
&fill_with_tie();
    
##############################################
### Ende sofort ausgefuehrte Subroutines 
##############################################



MainLoop;    

######################################################
sub fill_from_file {
    
    my $file = "meinfile.txt";
    my $line;
    
    $liste->delete(0,"end");
    
    if ( -s $file ) {
        open(DATEI, "<$file") or die $!;
        
        while ($line = <DATEI>) {
            chomp $line;
            $liste->insert(0,$line);
        }
        close(DATEI);
    } ## if -s $file

} ## fill_from_file #################    
############################################################        
    


######################################################
sub fill_with_tie {
    
    my $file = "meinfile.txt";
    my $line;
    my $elem;
    
    $liste->delete(0,"end");
    
    if ( -e $file ) {
        tie @array_file, "Tie::File", $file || die $!;
        
        foreach $elem (@array_file) {
            
            chomp $elem;
            $liste->insert(0,$elem);            
    
        } ## foreach
        
        untie @array_file;


    } else {
        print "Kann $file nicht oeffnen $!\n";
    } ## if -s $file
    
} ## fill_with_tie #################        
############################################################
[download]

Comment on listbox refresh with Tk::After Download Code

Replies are listed 'Best First'.
Re: listbox refresh with Tk::After by Khen1950fx (Canon) on Jul 28, 2007 at 00:45 UTC
I'd put in a repeat like this: `#!/usr/bin/perl use strict; use warnings; use Tk; use Tie::File; use Tk::After; #... my $liste = $frame1->ScrlListBox( #... )->pack( -side => "right", -expand => 1, -fill => "both" ); $liste->repeat( 5000, \&fill_from_file );` [download]	[reply] [d/l]
Re: listbox refresh with Tk::After by zentara (Cardinal) on Jul 28, 2007 at 11:07 UTC
Yeah, the Tk::after and Tk::repeat modules can be a source of confusion for a beginner. There is no perldoc for Tk::repeat, yet it is what is most often used. If you read perldoc Tk::after, you will see `$id = Tk::After->new($widget, tid, $time, ’once’, callback); $id = Tk::After->new($widget, tid, $time, ’repeat’, callback); $id->cancel; once or repeat specifies whether the timer is a one-time-after event, or a repeating repeat event.` [download] It just became a shortcut to write `$id = $mw->repeat( 10, sub{} );` [download] As far as your script goes, you might want to checkout the listbox -textvariable option to tie an array `#!/usr/bin/perl -w use strict; use Tk; my $mw = Tk::MainWindow->new( -title => 'Listbox' ); my @array = ('A'..'Z'); my $lb = $mw->Scrolled('Listbox', -listvariable => \@array, )->pack(); my $b = $mw->Button( -text => 'Delete B', -command => sub{ del_it('B') }, )->pack(); MainLoop; sub del_it { my $remove = shift; @array = grep { $_ ne 'B' } @array; } ##################################################################` [download] that way, you can just load your array from the file `open FH, '< myfile' or warn "$!\n" ; my (@array) = <FS>; close FH; $listbox->update; # may not be needed` [download] I'm not really a human, but I play one on earth. Cogito ergo sum a bum	[reply] [d/l] [select]