Anonymous Monk has given sensible suggestions, but I'll add to that (including, I hope, a better mod on the thread title).

I don't use 5.18 yet, so I'm not sure about this "lexical sub" you speak of, but with older versions, I think there's a "morally equivalent" approach that might have the properties that you're looking for. The following works for me in 5.12 (and presumably works in any Perl 5):

# TryMe.pm
package TryMe;

use strict;
use warnings;

sub new {
    my %obj = ( name => "TryMe", purpose => "None that I know of" );
    return bless \%obj;
}

sub do_something {
    my ( $class, $with_something ) = @_;
    my $special_trick = sub { "... this is only a test " };
    my $return_value = "Here's how I do_something $with_something:\n";
    for ( 1 .. 3 ) {
        $return_value .= &$special_trick;
    }
    $return_value;
}
1;
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Note how I assign an anonymous sub to a lexically scoped variable. Here's a simple use case:

#!/usr/bin/perl
use strict;
use warnings;

use TryMe;

my $tester = TryMe->new();

print $tester->do_something( "nice" ), "\n";
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