package My;

use strict;
use warnings;

my $pkg_sub = __PACKAGE__ . '::A';

# some methods for package My...

{
    no strict 'refs';
    *{$pkg_sub . '::new'} = sub {
        my $class = shift;
        return bless {ref($_[0]) ? %{$_[0]} : @_}, $class;
     };

    *{$pkg_sub . '::greet' } = sub { print 'Hello ' . shift()->{'name'} . ".\n"; };
}

1;

package main;

my $mya = My::A->new({name => 'Dave'});
$mya->greet();


##</code><code>##

my %subs = (
    new   => sub { # constructor goes here... },
    greet => sub { # Greeter goes here... },
);

while (my ($name, $code) = each %subs) {
    no strict 'refs';
    *{$pkg_sub . '::' . $name} = $code;
}

##</code><code>##

{
    # ...

    no strict 'refs';
    
    # ...

    while (my ($name, $code) = each %methods){
      *{"$class"."::"."$name"} = $code;
    }
  }