#!/usr/bin/perl
use strict;
use warnings;

package main;

my $foo = { bla => { foo => { bar => "a"} } };

check($foo);

sub check {
my $bla = shift;
my @key;
if(ref($bla) eq 'HASH') {
        @key = keys %{ $bla };
        print "<<$key[0]>>\n";
#       tie %{ $bla }, "myTieHash";
        $bla = $bla->{$key[0]};
        check($bla);
}
}

package myTieHash;

#Konstruktor für ein Hash Tie
sub TIEHASH {
        my $class = shift;
        my $self = { @_ };
        return bless $self, $class;
}

#Routine für den Schreibzugriff
sub STORE {
        my $self = shift;
        my ($key, $value) = @_;
        return $self->{ucfirst lc $key} = $value;
}

#Routine für den Lesezugriff
sub FETCH {
        my ($self, $key) = @_;
        return $self->{ucfirst lc $key};
}

1;