I just wanted to highlight why it makes sense that assigning to @_ doesn't write thru to the aliases.

my and local were already mentioned in my footnote, when using typeglobs I'd strongly suggest to prefer *b = \$a; over  *b = *a;

But these mechanisms are no big help if you want named parameters in subs cause those are lexicals, (which should be the preferred variable flavor).

> I'd not be surprised at all if there were CPAN modules that implemented this.

see Data::Alias or Lexical::Alias and their discussion in PBP

Perl6 aims to handle aliasing consistently.