#in class A
sub do_stuff{
    
   my $self = shift;  #1

   Class::B->do_things(sub{
                       my $self = @_; #2 
                  
                       my $blah = Class::C->blah({
                                   arg1=>$self->{blah}, #3
                                   arg2=>self->{wibble}
                                                 })    
                      }) 
}