in reply to Scalar and void subroutines

There must be something more here eff_i_g for it to be important to distinguish between void and scalar context.

Your sample code doesn't distinguish between void and scalar context of course. It simply provides a (somewhat hacky) way of signaling to the sub that you don't want a value returned. You could do something similar in a rather more up front way by:

do_something_to(\$this_var, 'No return required');

sub do_something_to {
if (! $#_)
  {
  $$_[0] = 'x';
  return;
  }

return 'x';
}

[download]

but that's pretty ugle really :).

Perl is Huffman encoded by design.

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Re^2: Scalar and void subroutines
by eff_i_g (Curate) on Nov 10, 2005 at 21:29 UTC
    You're right; my description was iffy. What I meant was:

    If called in void context, I am expecting a reference to be passed.
    If called in scalar context, I am expecting... either, actually, but there must be a reference in void.

    Sorry about that.
[reply]

      So you could:

      

sub name {
  die 'ref arg required in void context' if ! defined wantarray and ! 
+ref $_[0];
  my ($arg) = @_;
  if (ref $arg) {
    $$arg = 'x';
    return;
  }

  return 'x';
}

      [download]

      as a check that you've got a ref param in void context.

      Perl is Huffman encoded by design.
[reply]
[d/l]

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