use Perl

• What will the end user see... (Score:1)

  by Alias (5735)

  I'm throwing in my vote for scalar sort just returning list length.
  
  But why, it seems so pointless and a waste of CPU.
  
  The answer is that from the OUTSIDE of the method call, the user doesn't necesarily know that it went through sort, or whether the data for the list came pre-sorted.
  
  All they know is that they called a method and it returned a list. And the general assumption will be that scalar of it returns the quantity.
  
  As for wasting CPU with the sort, who's to know that the sort doesn't create some form of
  • Re: (Score:1)

    by Aristotle (5147)

    I’d say to skip sorting and return the number of elements efficiently. It would help the common case (return sort in scalar context), and I’ve never written a sort block with side effects, can’t imagine what it’d be useful for, or have seen any such thing in anyone else’s code, whether on PerlMonks or the CPAN.

    I believe that unlike being undefined in scalar context, not sorting in scalar context is a kind of surprise that’s not very surprising, and if anyone really need
    • Oh no, side effects. (Score:2)

      by schwern (1528)

      Someone's going to bring up side effects and point out that we're swapping one gotcha for another. The new gotcha being "sort in scalar context will not execute your code block, so if it has side effects they will not occur".
      
      The defense to that is that side effects in sort are so rare that this is hardly a real world gotcha. Does anyone put side effects in their sort?
      • Re: (Score:1)

        by Aristotle (5147) <pagaltzis@gmx.de> on 2006.02.10 18:18 (#46124) Homepage Journal

        I wouldn’t worry about that.

        First: we’re not trading gotchas:

        $ perl -le'@x = sort {++$_; $a cmp $b} qw(foo bar baz); print $_ || "nada"'
3
$ perl -le'$x = sort {++$_; $a cmp $b} qw(foo bar baz); print $_ || "nada"'
nada

        This is already part of the “sort in scalar context is undefined” gotcha.

        Second – and as I’ve said –, I’ve never wanted to use side effects in a sort block, I can’t imagine a good reason that needs it, and I’ve never seen anyone else do it on PerlMonks or other fora.

        For obvious reasons I won’t claim with certainty that noone does this. But I’d be willing to bet money that the number of instances where this would cause a problem are so vanishingly rare as to be ignorable.

        Unfortunately the CPAN code search currently throws 500 Internal Server Error when searching on phrases, and I have no minicpan set up either. So someone else will have to look for hard numbers, if they’re necessary.

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