in reply to creating defined references to arrays of size zero

My interpretation of what you are looking for is : 
my %stacks;

my $CurrentArrayRef = $Stacks{nonexistant} || []; 
# Line above CREATES a ref to an empty array if the stack was undefine
+d.
#It returns a ref to the contents if there were any.

push @$CurrentArrayRef, "New Value"; 
 ... more code ...

# Now (re)store the contents into the stack
$Stacks{nonexistant} = $CurrentArrayRef;

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Re^2: creating defined references to arrays of size zero
by tlm (Prior) on Jul 14, 2005 at 05:41 UTC 

    my $CurrentArrayRef = $Stacks{nonexistant} || [];

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    Better yet: 

    my $CurrentArrayRef = $Stacks{ nonexistant } ||= [];

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    This initializes $Stacks{ nonexistant } conditionally, and assigns its value to $CurrentArrayRef, thereby making this line: 
    # Now (re)store the contents into the stack
$Stacks{nonexistant} = $CurrentArrayRef;

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    unnecessary.

    the lowliest monk

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