liverpole,
I didn't read your entire post, just a couple of lines.

Having said that, though, there is one exception: an empty string will NOT work,...

I am not sure where you got that idea but an empty string works fine: 
#!/usr/bin/perl
use strict;
use warnings;
my %hash;
$hash{''} = 'foo';
print $hash{''};

[download]

But I'm still very curious -- how on earth did such a question occur to you?

My guess would be due to a background in another language. Certain C libraries have restriction on hash key length for instance while Java allows you to store objects as hash keys .

Cheers - L~R

In reply to Re^2: Hash key string restrictions? by Limbic~Region
in thread Hash key string restrictions? by Ojosh!ro

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