Question

I want to implement a history/recent-files functionality for my Perl/Tk program.

Here is a working code excerpt from my program to demonstrate my problem.

#!/usr/bin/perl 

use strict;
use warnings;
use English qw( -no_match_vars );

use Tk;

my @history_entries = qw(Back To The History);

my $mw      = MainWindow->new();
my $menubar = $mw->Menu();
$mw->configure( -menu => $menubar );
my $file    = $menubar->cascade( -label => '~File' );
my $history = $file->cascade( -label => '~History', );

build_history();

MainLoop();

#===  FUNCTION  ================================================================
#         NAME:  build_history
#      PURPOSE:  Polulate the history
#===============================================================================
sub build_history {
    foreach (@history_entries) {
        $history->command(
            -label    => $ARG,
            -command  => \&some_function,
            -compound => 'left',
        );
    }
    return;
}    # ----------  end of subroutine build_history  ----------

As you can see, the entries are created with $history->command but how can I delete them every time I call build_history?

The reason I want them deleted is that everytime a user opens a file, the last item (in this case ‘History’) should be deleted and a new item should be put on top of the list. So that I have a maximum of (in this example) four entries.

Any other ways of implementing this functionality with Tk are welcome.

Thanks for your time.

UPDATE:
I followed the advice of “mu” and tried to get the subwidgets with the children() function just after the function is called, like this:

my @child = $history->children();
foreach my $c ( @child ) {
    if ($c->Exists()){
        $c->destroy;
    }
}

The program exits with the error:

Can't locate object method "children" via package "Tk::Menu::Cascade" at /home/alex/Desktop/stack_history.pl line 28.

Answer 1

I ended up rebuilding the whole menu. That’s how my code looks like atm. I am not proud of it but it works … I am open to any form of advice.

#!/usr/bin/perl 

use strict;
use warnings;
use English qw( -no_match_vars );

use Tk;

# History entries are stored in array
my @history_entries = qw(Back To The History);

my $mw = MainWindow->new();
$mw->geometry('200x200');

my $menubar = $mw->Menu();

#Build menus
$mw->configure( -menu => $menubar );
build_menu();

$mw->Button(
    -text    => 'Update History',
    -command => \sub {

        #when a user opens a file insert_history is called.
        insert_history();
    }
)->pack( -side => 'bottom', -anchor => 'sw' );

MainLoop();

#===  FUNCTION  ================================================================
#         NAME:  build_menu
#      PURPOSE:  Update/Build the menu
#===============================================================================
sub build_menu {

    #delete the whole menu
    $menubar->delete(1);

    #built it again
    my $file = $menubar->cascade( -label => '~File' );
    my $history = $file->cascade( -label => '~History', );
    foreach (@history_entries) {
        $history->command(
            -label    => $ARG,
            -compound => 'left',
        );
    }

    return;
}    # ----------  end of subroutine build_menu  ----------

#===  FUNCTION  ================================================================
#         NAME:  insert_history
#      PURPOSE:  Do something with the array containing the history entries.
#                Then rebuild the menu.
#===============================================================================
sub insert_history {

    #make something with the array
    my $last_element = pop @history_entries;
    unshift @history_entries, $last_element;

    #update menu
    build_menu();
    return;
}    # ----------  end of subroutine insert_history  ----------