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: (Score:1)

      by n1vux (1492)

      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;
      • Re: (Score:1)

        by DAxelrod (4649)

        Since undef is false, wouldn't if (ref $thingy work in all cases?
        • Re:Legacy (Score:1)

          by emazep (6092) on 2006.10.28 7:01 (#51337) Journal

          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, or superfluous (pick your favorite), since ref never returns undef.

          In other words I mean that there is no reason to say

          if (defined ref $thingy && ref $thingy eq 'HASH') { ... }

          since

          if (ref $thingy eq 'HASH') { ... }

          gives no warnings as well (at least today), and it is less cluttered and more readable (and a little bit faster too ;-)

          Ciao, Emanuele.

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          Parent

          • 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.