in reply to when to use lists/hash vs references?

Not the only, and maybe not the most important, but here's one reason. The extra dereference costs: 

c:\test>p1
@a = map[1..3],1..1e6;;
$r = \@a;;

cmpthese -1, {
    a=>q[ ++$a[$_][1]   for 0..$#a ], 
    b=>q[ ++$r->[$_][1] for 0..$#$r ]
};;
    Rate    b    a
b 3.94/s   -- -16%
a 4.72/s  20%   --

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Another is that the extra syntax can get unwieldy for involved expressions.

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Re^2: when to use lists/hash vs references?
by chromatic (Archbishop) on Jul 16, 2010 at 00:30 UTC
    The extra dereference costs...

    So does the stack manipulation to pass or return a large list.

[reply]

      Of course. So don't do that.

      Declare an array, and pass a reference.

      I also prefer to use 

      sub arrayManip {
    our @a;
    local *a = shift;
    # do stuff with @a
}

my @array = (...);

arrayManip( \@array );

      [download]

      But you doubtless consider that too "complex".

[reply]
[d/l]
        But you doubtless consider that too "complex".

        I consider it a silly micro-optimization, because the programs I write tend to do IO. (And did you benchmark the cost of accessing the symbol table versus a lexical variable?)

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