in reply to Re: Better expression for $x = !!$y||0
in thread Better expression for $x = !!$y||0

Like others in this thread, you too are presuming the sanity of the ! return. In fact, ! can return 37 for true. There's no promise in the Perl docs otherwise.

-- Randal L. Schwartz, Perl hacker
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  • Comment on Re^2: Better expression for $x = !!$y||0

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Re^3: Better expression for $x = !!$y||0
by ysth (Canon) on Apr 19, 2005 at 23:08 UTC
    I said shorter, I didn't say accurate :). But really, if you presume an overloaded ! that returns something other than perl's true and false values (and that's presuming an awful lot) there's nothing you can do to $y besides examine it in boolean context with if or ?:.
[reply]
      Just to let you know we fixed this, in Perl 6 this is written: 
          $x = ?$y;

      [download]
      And the standard operators like == are expected to return 0 or 1 when a boolean result is expected. (Boolean context will still accept any true value, as in Perl 5, and the short-circuit operators still return one of the input values as the "true" value.),

      Yes, you can still overload these to return something other than 0 or 1, but it would be construed as antisocial.

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        in Perl 6

        ...

        Yes, you can still overload these to return something other than 0 or 1, but it would be construed as antisocial.

        That's exactly how I feel WRT doing this in perl5.
[reply]
      I said shorter, I didn't say accurate.
      If it doesn't need to be accurate, $x=1 is pretty short.
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