my %f;
%f=(One=>1,
    two=>sub{$f{One}}
);

# Flatten all the subs ..
ref $f{$_} eq 'CODE' and $f{$_}=$f{$_}->() for keys %f;

print Dumper \%f; # All populated

##</code><code>##

$VAR1 = {
          'two' => 1,
          'One' => 1
        };

##</code><code>##

my %f;
%f=(One=>{this=>'that'},
    two=>sub{$f{One}});