If all you really want is whether the hash is empty, you can call FIRSTKEY directly. 
#!/usr/bin/perl -w
use strict;
use TieTest;

my %h;
tie %h, 'TieTest';
$h{$_} = $_ for 0..9;

print defined scalar tied(%h)->FIRSTKEY
      ? "Not empty\n"
      : "Empty\n";

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In reply to RE: Whither the truth of a tied hash? by takshaka
in thread Whither the truth of a tied hash? by mojotoad

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