我有一个情况，在子类中，我需要引用在父类中定义的子例程，我需要将其传递给其他将执行它们的类。因此，我写了以下示例模块来进行测试。

父母1.pm

package Parent1;

sub new {
    my ($class, $arg_hash) = @_;

    my $self = bless $arg_hash, $class; 

    return $self;
}

sub printHello{

    print "Hello\n";
}

sub printNasty{
    print "Nasty\n";
}
1;            

下午1点

package Child1; 

use base Parent1;

sub new {
    my ($class, $arg_hash) = @_;

    my $self = bless $arg_hash, $class; 

    return $self;
}

sub testFunctionReferences{

    my ($self) = @_;

    # Case 1: Below 2 lines of code doesn't work and produces error message "Not a CODE reference at Child1.pm line 18."
    #my $parent_hello_reference = \&$self->SUPER::printHello;
    #&$parent_hello_reference();

    # Case 2: Out of below 2 lines of code, 1st line executes the function and produces output of "Hello\n" but 2nd line doesn't work and produces error message "Not a CODE reference at Child1.pm line 23."
    #my $parent_hello_reference2 = \$self->SUPER::printHello;
    #&$parent_hello_reference2();

    # Case 3: does not work either. Says "Undefined subroutine &Child1::printNasty called at Child1.pm line 27"
    #my $parent_nasty_reference = \&printNasty;
    #&$parent_nasty_reference();

    # Case 4: works. prints "World\n" as expected  
    #my $my_own_function_reference = \&printWorld;
    #&$my_own_function_reference();

    # Case 5: works. prints "Hello\n" and  "Nasty\n" as expected
    #$self->printHello();
    #$self->SUPER::printNasty();

    # Case 6: does not work produces error "Undefined subroutine &Child1::printHello called at Child1.pm line 38" 
    #printHello();
    return;
}

sub printWorld{
    print "World\n";
}   

test.pl

#!/usr/bin/perl

use Child1;

my $child = Child1->new({});

$child->testFunctionReferences();

所以我的问题是：

1. 与情况1一样，获得对父子例程的引用的正确语法是什么？

2. 使用继承时，如何像情况6一样直接调用父函数？在perl中甚至可能吗？

3. 当情况5有效时，为什么不进行情况6？

任何见解均表示赞赏。谢谢