I think this is backwards. If you're thinking of $myargs to literally unpack to conform to caller semantics, then I'd lose that notion. Just unpack the contents of $_[1] as needed in the resolved subroutine that ends up being called.

use strict;
use warnings;

package Foo;

sub new {
  my $pkg = shift;
  my $self = {};
  return $self, $pkg;
}

sub dispatch {
  my ($self, $mysub, $myargs) = @_;
  $self->$mysub($myargs);
  return;
}

sub mysub1 {
  my ($self, $args) = @_;
  foreach my $arg (split /,/, $args) {
    print qq{$arg\n};
  }
}

package main;

my $foo = Foo->new;
$foo->dispatch('mysub1', '1,2,3');
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Output

prompt$ perl test.pl
1
2
3
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