Perl revision 5 version 16 subversion 3

Greetings, oh Great Ones!

Here is a sort command that is barfing on me: 

my @ptn_sortd = sort {    ${$partition_h{a}}{full_tabname}
                      cmp ${$partition_h{b}}{full_tabname}} @parnums;

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This is greeted with a barrage of this error message: 
Use of uninitialized value in string comparison (cmp) at ./<script nam
+e> line 156.
 at ./<script name> line 156.
Use of uninitialized value in string comparison (cmp) at ./<script nam
+e> line 156.
 at ./<script name>l line 156.
Use of uninitialized value in string comparison (cmp) at ./<script nam
+e> line 156.
 at ./<script name> line 156.
....

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I have already proven that no item in the hash has an undefined {full_tabname} member. I used 

  grep {defined(${$partition_h{$_}}{full_tabname}) }

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to weed out the one such holdout. (That undefined name is separate mystery, out of scope for this question.) I have also confirmed that when I supply an actual value, the syntax does indeed return a string.

By the way, the hash keys are large-ish integers.

What could I possibly be doing wrong to deserve this frustrating punishment?

Thanks much for help here! -- RP

In reply to Debug a sort block by rpaskudniak

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