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    <p>The use of <code>shift</code> to unpack arguments is not evil. It's a common convention and may be the fastest way to process arguments (depending on how many there are and how they're passed). Here's one example of a somewhat common scenario where that's the case: a simple accessor.</p> <pre><code>use Benchmark qw(cmpthese); sub Foo::x_shift { shift-&gt;{'a'} } sub Foo::x_ref { $_[0]-&gt;{'a'} } sub Foo::x_copy { my $s = $_[0]; $s-&gt;{'a'} } our $o = bless {a =&gt; 123}, 'Foo'; cmpthese(-2, { x_shift =&gt; sub { $o-&gt;x_shift }, x_ref =&gt; sub { $o-&gt;x_ref }, x_copy =&gt; sub { $o-&gt;x_copy }, }); </code></pre> <p>The results on perl 5.8.8 on my machine:</p> <pre><code> Rate x_copy x_ref x_shift x_copy 772761/s -- -12% -19% x_ref 877709/s 14% -- -8% x_shift 949792/s 23% 8% -- </code></pre> <p>Not dramatic, but there it is. Always test your scenario on your version of perl on your target hardware to find out for sure.</p> <p><code>shift</code> is also useful in cases where you want to shift off the invocant and then call a <code>SUPER::</code> method, passing the remaining <code>@_</code> as-is.</p> <pre><code>sub my_method { my $self = shift; ... return $self-&gt;SUPER::my_method(@_); } </code></pre> <p>If I had a very long series of <code>my $foo = shift;</code> operations at the top of a function, however, I might consider using a mass copy from <code>@_</code> instead. But in general, if you have a function or method that takes more than a handful of arguments, using named parameters (i.e., catching all of <code>@_</code> in a <code>%args</code> hash or expecting a single hash reference argument) is a much better approach.</p>
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    1. COYou should show when it's actually faster to no use shift. I think with either 2 or 3 args it's faster to copy @_. As a rule of thumb I use shift when there's 1 arg and copy @_ when there's more than 1.
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