The following is from an e-mail I sent to an individual who wrote an online perl tutorial

--begin snip--

I was looking at your site ( www.sysarch.com ... hash_slices.txt) for good examples of hash slices when I came across the following code:

          
          @array = qw( a b c d ) ;
          
          @array{ @array } = ( [ @array ] ) x @array ;
[download]

With the explanation:

          
          
             ...this means the
                  hash %array looks like this:
          
          %array = (
              'a' => [ 'a', 'b', 'c', 'd' ],    
              'b' => [ 'a', 'b', 'c', 'd' ],    
              'c' => [ 'a', 'b', 'c', 'd' ],    
              'd' => [ 'a', 'b', 'c', 'd' ],    
          ) ;
[download]

Actually this is FALSE. Your original code does not create four separate anonymous array references but four entries that point to the same hash reference. Debugging reveals the error:

          
            DB<1> n
          main::(-e:1):   @array = qw( a b c d ) ;@array{ @array } = (
+ [ @array ] ) x @array ; print $array{'a'}->[1];
            DB<1>
          main::(-e:1):   @array = qw( a b c d ) ;@array{ @array } = (
+ [ @array ] ) x @array ; print $array{'a'}->[1];
            DB<1> x %array
          0  'a'
          1  ARRAY(0x1d7f550)
             0  'a'
             1  'b'
             2  'c'
             3  'd'
          2  'b'
          3  ARRAY(0x1d7f550)
             -> REUSED_ADDRESS
          4  'c'
          5  ARRAY(0x1d7f550)
             -> REUSED_ADDRESS
          6  'd'
          7  ARRAY(0x1d7f550)
             -> REUSED_ADDRESS
            DB<2>
[download]

And a test confirms this:

          
          C:\>perl -e "@array = qw( a b c d
           ) ;@array{ @array } = ( [ @array ] ) x @array ; $array{'a'}
+->[1] = 'FOOBAR'; print $array{'a'}->[1]; print $array{'b'}->[1];"
          FOOBARFOOBAR
[download]

--end snip--

It was a bummer that I could not use the syntax given to get a hash of anonymous arrays that are different. Here's my question, how do you get four anonymous arrays using similar syntax?

Celebrate Intellectual Diversity

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