use feature ":5.14";
use warnings FATAL => qw(all);
use strict;
use Data::Dump qw(dump);

sub Mine()
 {package __SUB__;
  eval "sub $_ {say \"$_\"}" for qw(hello goodbye);
  bless {}
 }

my $a = Mine();
$a->hello();
$a->goodbye();
  
__END__
Produces:
hello
goodbye