I've run into the same error message numerous times while trying to setup hashes for my various gui programs. Look at this simple example, and see that only line 13 causes an error.

It is sort of confusing to me as to why, but if you have a multi-level hash, the first key must be able to vary, it cannot be a scalar reference to some other data structure or object. 

#!/usr/bin/perl 
use warnings;
use strict;

my %hash;
my @array = (1..100);

# this will be ok
$hash{\@array} = 42;

# but this will issue an error, because \@array 
# cannot be used as a key which varies
$hash{\@array}{1} = 42;

# this will be ok
$hash{1}{\@array}{1} = 42;

#this will be ok
$hash{1}{\@array}{1}{1} = 42;

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In reply to Re: can't use string as hash ref by zentara
in thread can't use string as hash ref by spickles

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