use Data::Dumper;
my $hashref={
  ...., 
  k1 => { 
    ....
    k2 => {
      ....
      kN => {...., mydata => MyClass->new(), .... }}}};
print(Dumper($hashref));

##</code><code>##

....
    mydata => bless(..., 'MyClass')
....

##</code><code>##

....
    mydata => 'MyOwnRepresentation of the MyClass instance'
....

##</code><code>##

sub MyClass::myfreezer { ... }
$Data::Dumper::Freeze='myfreezer'