in reply to Printing a subset of a data structure

I think what you're trying to achieve here (correct me if I'm wrong) is to display a submenu only when it's needed, i.e. if the user has selected an item from the main menu which has a submenu. To do this, you're wanting to defer the printing of a submenu. Your code, as shown, does not acheive this; even though you're taking a reference to the print_sub_menu function, you're still calling it right away, and putting the result in the data structure. Instead, you should put a code reference in the data structure. E.g.: 

my %menus = (
  '1' => {
    'ITEM'    => 'List and Kill UDT* processes by user',
    'ACTION'  => sub { $RunCMD->('ListKillProc') },
  },

  '2' => {
    'ITEM'    => 'List and Kill Print Jobs',
    'ACTION'  => sub { $PrintSubmenu->('2') },
    . . .

[download]

Then, when the user selects an item, you can execute the action; something like this: 

    $menu->{$MenuItem}->{'ACTION'}->();

[download]

Other than that, there's a lot you could do to this to make it more generic and robust.

Might I also suggest that you're suffering from (or inflicting) Indentation Hell. Try it this way: 

my %menus = (
    '1' => {
        'ITEM'    => 'List and Kill UDT* processes by user',
        'ACTION'  => $RunCMD->('ListKillProc'),
    },

    '2' => {
        'ITEM'    => 'List and Kill Print Jobs',
        'ACTION'  => $PrintSubmenu->('2'),
        'SUBMENU' => {
            '1' => {
                'ITEM'   => 'Show all Printers',
                'ACTION' => $RunCMD->('showprintersall'),
            },
            '2' => {
                'ITEM'   => 'Show user print jobs',
                'ACTION' => $RunCMD->('showprintersuser'),
            },
            '3' => {
                'ITEM'   => 'Show single printer',
                'ACTION' => $RunCMD->('showprinter'),
            },
            '4' => {
                'ITEM'   => 'Kill a print job',
                'ACTION' => $RunCMD->('killprint'),
            },
        }
    },

    '3' => {
        'ITEM'    => 'Manage user accounts',
        'ACTION'  => $PrintSubmenu->('3'),
        'SUBMENU' => {
            '1' => {
                'ITEM'   => 'Unlock user account',
                'ACTION' => $RunCMD->('unlockuser'),
            },
            '2' => {
                'ITEM'   => 'Change account password',
                'ACTION' => $RunCMD->('changepass'),
            },
        },
    },

    '4' => {
        'ITEM'    => 'Run App',
        'ACTION'  => $RunCMD->('APP'),
    },
                                                         
    '5' => {
        'ITEM'    => 'quit',
        'ACTION'  => $RunCMD->('quit'),
    },
);

[download]
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Simple Console Menuing System
by jdporter (Paladin) on May 01, 2006 at 17:49 UTC

    Inspired by the OP, I wrote the following. It's a system for simple console-based menus. It's easily extensible. 

    use strict;
use warnings;

sub do_menu
{
    my( $menu ) = @_;
    while(1)
    {
        my( $menu ) = @_;
        # display the menu
        print "\n";
        print $_+1, '. ', $menu->[$_]{'label'}, "\n"
            for 0 .. $#{$menu};
        print '0. ', ( @_ > 1 ? 'Return' : 'Exit' ), "\n";
        # get the user's input
        local @ARGV;
        print STDERR '> ';
        local $_ = <>; chomp;

        /\d/ && !/\D/ or next;
        $_ == 0 and last; # item 0 is special
        defined $menu->[$_-1] or warn("Invalid choice\n"), next;

        my $op = $menu->[$_-1]{'op'};
        my $arg = $menu->[$_-1]{'arg'};
        if ( $op eq 'submenu' )
        {
            do_menu( $arg, @_ ); # maintain the stack!
        }
        elsif ( $op eq 'exec_cmd' )
        {
            execute_command( $arg );
        }
        else
        {
            warn "Unrecognized op '$op'\n";
        }
    }
}


my @printers_menu = (
    {
        label => 'Show all Printers',
        op => 'exec_cmd',
        arg => 'showprintersall',
    },
    {
        label => 'Show user print jobs',
        op => 'exec_cmd',
        arg => 'showprintersuser',
    },
    {
        label => 'Show single printer',
        op => 'exec_cmd',
        arg => 'showprinter',
    },
    {
        label => 'Kill a print job',
        op => 'exec_cmd',
        arg => 'killprint',
    },
);

my @accounts_menu = (
    {
        label => 'Unlock user account',
        op => 'exec_cmd',
        arg => 'unlockuser',
    },
    {
        label => 'Change account password',
        op => 'exec_cmd',
        arg => 'changepass',
    },
);

my @main_menu = (
    {
        label => 'List and Kill UDT* processes by user',
        op => 'exec_cmd',
        arg => 'ListKillProc',
    },
    {
        label => 'List and Kill Print Jobs...',
        op => 'submenu',
        arg => \@printers_menu,
    },
    {
        label => 'Manage user accounts...',
        op => 'submenu',
        arg => \@accounts_menu,
    },
    {
        label => 'Run App',
        op => 'exec_cmd',
        arg => 'APP',
    },
);

sub execute_command
{
    warn "Executing command '@_'\n";
}

do_menu( \@main_menu );

    [download]

    Of course, with objects, this might have been even more elegant.

    We're building the house of the future together.
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[d/l]

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