Thanks for looking into Perl and visiting the monastery. :)

something similar to CLOS before/around/after methods.

The v6.c version of the Perl 6 language is supposed to have a similar feature called `wrap` such that, given this code:

sub foo { say 42 }
&foo.wrap: { say 'before'; callsame; say 'after' }
foo;
[download]

The `foo` call in the last line displays:

before
42
after
[download]

The above is equivalent to a CLOS `:around`.

Be aware that, compared with Perl 5, Perl 6 is an immature upstart, and that's an understatement. I've tested that my v6.c compatible Rakudo (all Rakudos released in 2016 or later support v6.c) does the above correctly and I can see that a lot of simple cases are tested in S06-advanced/wrap.t but I also see lots of bugs in the bug queue with 'wrap' in their title, at least some of which are about this particular feature.

A search of modules.perl6.org for 'before' yielded Method::Modifiers. I see recent commits by the author. The project's modules are tiny examples of MOP programming. They're probably worth a look over even if you don't actually `use Method::Modifiers;`.

I see others have answered your other questions. Have The Appropriate Amount Of Fun....