in reply to Re: A most obscure bug
in thread A most obscure bug

As far as I can tell, it was broken from the beginning. I haven't managed to track down the original patch which added the implicit defined() feature though.

Can you remember when it was added? Was it during your reign, or later than that?

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Re: Re: Re: A most obscure bug
by chip (Curate) on Dec 19, 2001 at 23:18 UTC
    The automatic implied defined() was added after my time as pumpking. When I discovered the danger of while (<>) {}, I didn't feel I could change the language without breaking things, so I added a warning instead. That warning was unsatisfactory to a lot of people, so the issue came up again, this time during one of Larry's more available periods. Somebody proposed the language change we have today, Larry OK'd it, and the patch was installed almost immediately.

        -- Chip Salzenberg, Free-Floating Agent of Chaos

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      Interestingly, your warning is still in effect. The only way I can throw it is through this bug: 
      # OK, gets implied defined(), no warning, correct output
% perl -lwe 'print while glob("{dog,cat,0,pig,cow}")'

  dog
  cat
  0
  pig
  cow


# Buggy, no implied defined(), throws warning and misbehaves
% perl -lwe 'print while $_ = glob("{dog,cat,0,pig,cow}")'

  Value of glob construct can be "0"; test with defined() at -e line 1
+.
  dog
  cat

      [download]

      -Blake

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[d/l]

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