Is there any real need to use classes at all? You could just use one class and store the information which C-class it is for inside.

example:

package My::Types;

sub new {
  my $pclass = shift;
  my $cclass = shift;
  my $cself = $pclass->readFromData($cclass);
  my $pself = { cself => $cself, cclass => $cclass };
  return bless $pself, ref($pclass)||$pclass;
}

sub isSame {
    my $pclass = shift;
    my $other = shift;
    return undef unless $other->CORE::isa(__PACKAGE__);
    return $other->{cclass} eq $pself->{cclass};
}

sub getNumberOfParams {
  my $pself = shift;
  my $cself = $pself->{cself};
  return $cself->{noOfParm};
}

...

package main;

$a = My::Types->new('printf');
print $a->getNumberOfParams();
[download]

(untested code)

Update: Oops, I coded an isSame() method, not an isa(). Renamed it to avoid misunderstandings...