Delete the subwidgets/entries from a tk::menu widget - perl

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

you can create a submenu from the menubar first:
my $sub_menu = $menubar->Menu(-tearoff => 0);
Then you can pass this submenu to the cascade menuitem:
$file->cascade( -label => '~History', -menu => $sub_menu);
Then you can add/delete menuitems to the submenu:
foreach (#history_entries) {
$sub_menu->command(
-label => $ARG,
-compound => 'left',
);
}
...
$sub_menu->delete(0); # Remove first element
With this solution you can avoid rebulding the whole menu.

Answer 2

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 ----------