How would I delete hash keys only when the key has no values?

Question

I have built a loop that finds all of the VMDKs for a perticular VM and then create a hash of the output, then it tests whether the disk is actually present by looking for a parameter in the VMX file. Then if the disk is not present it deletes it from the hash. The problem I running into is how to delete a hash key that has no disks defined.

Here is the code block;

    while ($vmx_file =~ m/^(ide(?<PORT>[0-1])\:(?<DISK>[0-1]))\.present\s+=\s+"(?<PRESENT>[^"]+)["]/xmg) {
        $ide_port = "$+{PORT}";
        $ide_disk = "$+{DISK}";
        $present = "$+{PRESENT}";
        if ($present eq 'FALSE') {
            delete $virtual_disks{$vm}{"IDE$ide_port"}{"Disk$ide_disk"}
        }
    } 

This is what I am getting as a hash when the above statement is true and it deletes the missing disks.

$VAR1 = {
      'Test01' => {
                    'SCSI0' => {
                                 'Disk0' => '/vmfs/volumes/4c8fd27b-5876fc36-80f4-0015179fd63c/Test01/Test01.vmdk',
                                 'Type' => 'lsilogic',
                                 'Disk1' => '/vmfs/volumes/4c8fd27b-5876fc36-80f4-0015179fd63c/Test01/Test01_1.vmdk'
                               },
                    'IDE1' => {
                                'Disk0' => '/vmfs/volumes/4c8fd27b-5876fc36-80f4-0015179fd63c/ubuntu-10.10-desktop-i386.iso'
                              },
                    'IDE0' => {}
                  }

As you can see the sub hash 'IDE0" is empty, because the disk that was listed was not present in the VMX file. Now what I would like to do is remove the entire 'IDE0' hash because there is nothing in it. But I only want it to delete it if it hash nothing. becasue it can have up to 2 disks in it as per IDE specs. Follow me?

Answer 1

Count the remaining keys after your first round of deletion. If the count is zero, delete at the higher level.

 if (scalar keys %{ $virtual_disk{$vm}{"IDE$ide_port"} } == 0) {
      delete $virtual_disks{$vm}{"IDE$ide_port"}
        }