Question

Why does this script continue to run and not die, when I pass an invalid file-name?

#!/usr/bin/env perl
use warnings;
use 5.12.0;
use Getopt::Long qw(GetOptions :config bundling);

sub help {
    say "no help text";
}

sub read_config {
    my $file = shift;
    open my $fh, '<', $file or die $!;
    say <$fh>;
    close $fh;
}

sub helpers_dispatch_table {
    return {
        'h_help'                => \&help,
        'r_read'                => \&read_config,
    };
}

my $file_conf = 'does_not_exist.txt';
my $helpers = helpers_dispatch_table();

GetOptions (
    'h|help'            => sub { $helpers->{h_help}(); exit; },
    'r|read'            => sub { $helpers->{r_read}( $file_conf ); exit },
);

say "Hello, World!\n" x 5;

Answer 1

From perldoc Getopt::Long

   A trivial application of this mechanism is to implement options that are related to each other. For example:

       my $verbose = '';   # option variable with default value (false)
       GetOptions ('verbose' => \$verbose,
                   'quiet'   => sub { $verbose = 0 });

   Here "--verbose" and "--quiet" control the same variable $verbose, but with opposite values.

   If the subroutine needs to signal an error, it should call die() with the desired error message as its argument. GetOptions() will catch the die(),
   issue the error message, and record that an error result must be returned upon completion.