use Perl

• Legacy (Score:1)

  by Aristotle (5147)

  I think it used to return undef on older Perls, which is where that meme came from.
  • Re: (Score:1)

    by link (3402)

    It used to be documented as
    
    Returns a TRUE value if EXPR is a reference, FALSE otherwise.
    
    which could mean it returns "" or undef or alternates between them.
    • Re:Legacy (Score:1)

      by n1vux (1492) on 2006.10.27 13:27 (#51321) Homepage Journal

      which means removing the defined() without putting in a require 5.8.0; would potentially create a compatibility regression, on any implementation/releases that actually returned undef when FALSE was documented?
      
      Do we know if it actually returned 'undef' or if it always returned q{} as it's FALSE (but defined) value?

      --
      Bill
      # I had a sig when sigs were cool
      use Sig;

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      Parent

      • Re: (Score:1)

        by DAxelrod (4649)

        Since undef is false, wouldn't if (ref $thingy work in all cases?
        • Re: (Score:2)

          by bart (450)

          Sure it would. At least on the first page of results emazep's Code Search query, all code snippets take the form of

          if(defined ref $x && ref $foo eq 'X') ...

          This can be reduced to

          if(ref $x && ref $foo eq 'X') ...

          even if ref ever returned undef (which, last I heard, has always been considered false). Which it doesn't, even

          ref undef

          returns a true boolean, a value like !1. And then,

          if(ref $foo eq 'X') ...

          suffices. No warnings, now, ever. But maybe it did warn, in the past.
        • Re: (Score:1)

          by emazep (6092)

          Well, not always.

          Under the false assumption that if the argument is not a reference ref returns undef, a test like this

          if (defined ref $thingy) { ... }

          to check if $thingy is a reference or not, would clearly be wrong, non just redundant (you can find an example of this here [google.com]).

          Anyway my main complaint was about the fact that, even if the code is formally correct (whereas the test is used to supposedly avoid the possible warning from a subsequent test), such defined-ness test is redundant, or unnecessary,
          • Re: (Score:1)

            by emazep (6092)

            Update

            Please forget my previous pointless post: I wrongly assumed that DAxelrod was talking about

            if (defined ref $thingy) { ... }

            while he clearly said

            if (ref $thingy) { ... }

            Ciao, Emanuele.