You want a positional parameter to a subroutine to be either an array reference or a scalar. If it's a scalar it should be treated as a one element array. OK, so far.

What if you want to preserve the @_ aliasing?
Um...Just use @_?
Say you can't because you're using the rest of @_ for other parameters
(like another optional list).

Well if you find yourself in that improbable situation, you can use shift_list. 

sub routine {
    my $self = shift;
    my $list = &shift_list; # expose our @_
    # then @_ = ($other, $args)

    s/a/A/g for (@$list); # change the original
    ...
}

[download]
If there's other ways I'd like to know, this is a fishing expedition.
sub shift_list {
  # shift one element of @_ and return it as an array ref
  # PRESERVING the @_ aliasing
  # (if called like &shift_list we get the caller's actual @_)
  my $list;
  if(ref $_[0]) { 
    $list = shift;
    unless (ref $list eq 'ARRAY') {
      die "Not an array ref ($list)";
    }   
  } else { 
    # aliasing funkiness
    # pass aliased $_[0] to sub ref which returns a ref to it's @_
    $list = ( sub {\@_} )->($_[0]);
    shift; # for parent
  } 
  return $list;
}

[download]
(That weird ( sub {\@_} )->($_[0]) stuff is stolen from Damian's slice aliasing code posted to perl6-lang)

In reply to Preserve @_ aliasing a (scalar||array) by bsb

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