SYNOPSIS

my $change = Monorail::Change::AlterField->new(
    table => $from->table->name,
    from  => {
        name           => $from->name,
        type           => $from->data_type,
        is_nullable    => $from->is_nullable,
        is_primary_key => $from->is_primary_key,
        is_unique      => $from->is_unique,
        default_value  => $from->default_value,
        size           => $from->size,
    },
    to => {
        name           => $to->name,
        type           => $to->data_type,
        is_nullable    => $to->is_nullable,
        is_primary_key => $to->is_primary_key,
        is_unique      => $to->is_unique,
        default_value  => $to->default_value,
        size           => $to->size,
    }
);

if ($change->has_changes) {
    return $change->as_perl
}
else {
    return;
}