use Perl

• It's a well-known problem (Score:1)

  by Ed Avis (3134)

  Yes, this is a well-known problem with eval. You cannot, as the manual page suggests, do eval { ... } and then test $@ to see whether there was an error. The correct incantation is something like
  
  my $r = eval { ... };
  my $error = $@;
  $error //= 'unknown error' if not $r;
  if ($error) { ... }
  
  By well-known I mean known to a tiny minority of cognoscenti, while most perl programmers and the documentation are entirely ignorant of it. Which is the default situation for any trap or gotcha in the perl language. But

  --
  -- Ed Avis ed@membled.com
  • Re:It's a well-known problem (Score:1)

    by Ed Avis (3134) <ed@membled.com> on 2008.08.29 4:37 (#64650) Homepage

    Duuh, I meant
    
    my $r = eval { ...; 1 };
    my $error = $@;
    $error //= 'unknown error' if not $r;
    if ($error) { ... }
    
    Note the trailing '1' in the eval block.
    
    (It doesn't help that the comment engine here is doing something weird so you lose all your text if you go Back and Forward in Firefox. And those submit buttons are not buttons at all but look like links. What's going on?)

    --
    -- Ed Avis ed@membled.com

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