I think I should explain my problem a bit more in detail: I have a hash like 
my $test = (
    'a' => {
        'identifiers' => {
                                  'mrt1' => 1,
                                  'mrt2' => 1,
                                  'mrt3' => 1,
         },
    },
    'b' => {
        'identifiers' => {
                                  'mrt2' => 1,
                                  'mrt3' => 1,
                                  'mrt6' => 1,
         },
    },
    'c' => {
        'identifiers' => {
                                  'mrt1' => 1,
                                  'mrt2' => 1,
                                  'mrt3' => 1,
         },
    },
    'd' => {
        'identifiers' => {
                                  'mrt2' => 1,
                                  'mrt3' => 1,
                                  'mrt6' => 1,
         },
    },
    'sum_ab' => {
        'values' => {
                                  'a' => 1,
                                  'b' => 1,
         },
    },
    'sum_cd' => {
        'values' => {
                                  'c' => 1,
                                  'd' => 1,
         },
    },
    'sum_abcd' => {
        'values' => {
                                  'sum_ab' => 1,
                                  'sum_cd' => 1,
         },
    },
);

[download]
In case of mrt1 I do something, because a is matched. Afterwards I need to do something, because sum_ab has a in its 'values'-hash. Afterwards I have to check if some sum includes 'sum_ab' and so on...

That is the reason, why I wanted to use the nested iteration over the same hash. Perhaps I could push to some temporary variable and do the second while after the first one.

In reply to Re^4: Nested while each over a hash -> infinite loop by Eythil
in thread Nested while each over a hash -> infinite loop by Eythil

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